Infrastructure projects that intentionally use natural and nature-based habitats and processes to reduce risks and deliver multiple benefits are referred to as nature-based solutions.

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The ocean’s water is constantly circulated by currents. Tidal currents occur close to shore and are influenced by the sun and moon. Surface currents are influenced by the wind. However, other, much slower currents that occur from the surface to the seafloor are driven by changes in the saltiness and ocean temperature, a process called thermohaline circulation. These currents are carried in a large "global conveyor belt," which includes the AMOC.

AMOC stands for Atlantic Meridional Overturning Circulation. The AMOC circulates water from north to south and back in a long cycle within the Atlantic Ocean. This circulation brings warmth to various parts of the globe and also carries nutrients necessary to sustain ocean life.

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Lines of longitude, also called meridians, are imaginary lines that divide the Earth. They run north to south from pole to pole, but they measure the distance east or west.

The prime meridian, which runs through Greenwich, England, has a longitude of 0 degrees. It divides the Earth into the eastern and western hemispheres. The antimeridian is on the opposite side of the Earth, at 180 degrees longitude. Though the antimeridian is the basis for the international date line, actual date and time zone boundaries are dependent on local laws. The international date line zigzags around borders near the antimeridian.

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Lines of latitude, also called parallels, are imaginary lines that divide the Earth. They run east to west, but measure your distance north or south. The equator is the most well known parallel. At 0 degrees latitude, it equally divides the Earth into the Northern and Southern hemispheres. From the equator, latitude increases as you travel north or south, reaching 90 degrees at each pole.

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Barrier islands form as waves repeatedly deposit sediment parallel to the shoreline. As wind and waves shift according to weather patterns and local geographic features, these islands constantly move, erode, and grow. They can even disappear entirely.

They are generally separated from the mainland by tidal creeks, bays, and lagoons. Beaches and sand dune systems form on the side of the island facing the ocean; the side facing the shore often contains marshes, tidal flats, and maritime forests. These areas are important habitat for seabirds, fish and shellfish, and and nesting sea turtles.

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Scientists have suspected for a while that Greenland sharks lived extremely long lives, but they didn’t have a way to determine how long. The age of other shark species can be estimated by counting growth bands on fin spines or on the shark’s vertebrae, much like rings on a tree. Greenland sharks, however, have no fin spines and no hard tissues in their bodies. Their vertebrae are too soft to form the growth bands seen in other sharks. Scientists could only guess that the sharks lived a long time based on what they knew — the sharks grow at a very slow rate (less than 1 cm per year) and they can reach over 6 meters in size.

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Scientists estimate that 50-80% of the oxygen production on Earth comes from the ocean. The majority of this production is from oceanic plankton — drifting plants, algae, and some bacteria that can photosynthesize. One particular species, Prochlorococcus, is the smallest photosynthetic organism on Earth. But this little bacteria produces up to 20% of the oxygen in our entire biosphere. That’s a higher percentage than all of the tropical rainforests on land combined.

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The word “plankton” comes from the Greek for “drifter” or “wanderer.” An organism is considered plankton if it is carried by tides and currents, and cannot swim well enough to move against these forces. Some plankton drift this way for their entire life cycle. Others are only classified as plankton when they are young, but they eventually grow large enough to swim against the currents. Plankton are usually microscopic, often less than one inch in length, but they also include larger species like some crustaceans and jellyfish.

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Harmful algal blooms — often referred to as HABs for short — occur when algae produce toxic or harmful effects on people, fish, shellfish, marine mammals, birds, or other aquatic organisms. Blooms occur in marine and freshwater environments throughout the world, with damaging ecological, social, and economic effects. So why can’t we clean up the algae and take care of this problem? Unfortunately, the answer is not so simple. Harmful algal blooms are a natural process. There are records of HABs from early European colonists arriving to Florida in the 1500s. However, research points to an increase in the frequency and intensity of algal blooms in modern times due to environmental changes caused by humans.

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Did you know that near St. Augustine, Florida — the nation’s oldest city — there exists an actual “castle” made of sand? Located on 20.5 acres on the western shore of Matanzas Bay, the Castillo de San Marcos National Monument is the oldest (circa 1695) and largest masonry fort in the continental United States.

The Castillo’s masonry, or stonework, is largely comprised of coquina (Spanish for “small shells”) — a natural concrete derived from the ocean. Coquina is a rare form of limestone composed of the shell fragments of ancient mollusks and other marine invertebrates, which, over time, are glued together by dissolved calcium carbonate in the shells. Coquina is also the name of a common tiny clam found everywhere on Florida beaches. Their shells, which come in countless colors, are reflected in the Castillo’s muted hues.

A related building material is tabby, often called coastal concrete, which is basically manmade coquina. Tabby is composed of the lime from burned oyster shells mixed with sand, water, ash, and other shells. As far back as the 1600s, Spanish and English settlers used tabby to build their homes and other structures, and to pave their roads, throughout the coastal Carolinas, Georgia, and Florida.

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Carbon is the foundation of all life on Earth, required to form complex molecules like proteins and DNA. This element is also found in our atmosphere in the form of carbon dioxide (CO2). Carbon helps to regulate the Earth’s temperature, makes all life possible, is a key ingredient in the food that sustains us, and provides a major source of the energy to fuel our global economy.

The carbon cycle describes the process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere. Since our planet and its atmosphere form a closed environment, the amount of carbon in this system does not change. Where the carbon is located — in the atmosphere or on Earth — is constantly in flux.

Watch our animated video about the carbon cycle to get what you need to know in under two minutes.

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Sponges are animals with dense skeletons that are highly adapted to their environments, although it is easy to see why they may be mistaken for plants. Sponges are found in a wide variety of colors, shapes, and sizes – and scientists believe that the colors of the sponge may act as a protection from the sun’s harmful UV rays. Most sponges are found in the ocean, but there are certain sponge species that can be found in freshwater environments, as well.

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Formed in depressions along the shoreline of rocky coasts, tide pools are filled with seawater that gets trapped as the tide recedes. While these small basins at the ocean’s edge typically range from mere inches to a few feet deep and a few feet across, they are packed with sturdy sea life such as snails, barnacles, mussels, anemones, urchins, sea stars, crustaceans, seaweed, and small fish.

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The word “archipelago” comes from the medieval Italian word archi, meaning chief or principal, and the Greek word pelagus, meaning gulf, pool, or pond.

Most archipelagos are formed when volcanoes erupt from the ocean floor; these are called oceanic islands. The islands of the Hawaiian archipelago, for example, were formed by a series of volcanic eruptions that began more than 80 million years ago and are still active today.

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Intertidal zones exist anywhere the ocean meets the land, from steep, rocky ledges to long, sloping sandy beaches and mudflats that can extend for hundreds of meters. Four physical divisions, each with distinct characteristics and ecological differences, divide the intertidal zone.

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Broken bottles, discarded love letters, castoff clothing, candy wrappers, flotsam and jetsam washed ashore: During a walk along a beach, one finds any of these items and more. In all that litter, there is one item more common than any other: cigarette butts.

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Seasickness is a result of a conflict in the inner ear, where the human balance mechanism resides, and is caused by a vessel’s erratic motion on the water. Inside the cabin of a rocking boat, for example, the inner ear detects changes in both up-and-down and side-to-side acceleration as one’s body bobs along with the boat. But, since the cabin moves with the passenger, one’s eyes register a relatively stable scene. Agitated by this perceptual incongruity, the brain responds with a cascade of stress-related hormones that can ultimately lead to nausea, vomiting, and vertigo.

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Summertime means hot weather — sometimes dangerously hot — and extreme heat waves have become more frequent in recent decades. Sometimes, the scorching heat is ensnared in what is called a heat dome. This happens when strong, high-pressure atmospheric conditions combine with influences from La Niña, creating vast areas of sweltering heat that gets trapped under the high-pressure "dome."

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Though numerous lighthouses still serve seafarers, modern electronic aids to navigation play a larger role in maritime safety in the 21st century.

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A canal is a manmade waterway that allows boats and ships to pass from one body of water to another. Canals are also used to transport water for irrigation and other human uses. While the advent of more efficient forms of transportation has reduced the need for canals, they still play a vital role as conduits for transportation and foster global commerce.

There are two types of canals: waterways and aqueducts. Waterways are the navigable parts of a body of water, and can be located within a bay or open sea, can connect two or more waterbodies, or may even form networks within a city. Aqueducts are used exclusively to transport water for drinking, agriculture, and hydroelectric power.

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An island’s windward side faces the prevailing, or trade, winds, whereas the island’s leeward side faces away from the wind, sheltered from prevailing winds by hills and mountains. As trade winds blow across the ocean, they pick up moist air from the water.

Once the damp air makes landfall on an island, it ascends hills and mountains to form condensation, clouds, and precipitation. As the air moves to the other side of the island, it warms up and dries out. Thus, an island’s windward side is wetter and more verdant than its drier leeward side. Meteorologists call this contrast the orographic effect.

As an example, the Hawaiian Islands have damp windward sides and drier leeward sides most of the time as a result of the Pacific Ocean’s northeasterly trade winds. Windward locations are generally lush and green. Famously sunny beaches like Oahu’s Waikiki and Maui’s Wailea are found on the islands’ more sheltered leeward sides.

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While some places have one high tide and one low tide per day, most coastal locations have two high tides and two low tides a day. These highs and lows typically aren't equal. This is why, in most places, using the phrase "high tide" might be unclear. There's actually high tide and higher high tide (and low and lower low tide).

If the Earth were a perfect sphere without large continents, every place would get two equal high and low tides every day. However, the presence of the continents, regional geography and features on the seafloor, among other factors, make tidal patterns more complex.

Around the world, there are three basic tidal patterns: semidiurnal, mixed, and diurnal. When both high tides are about equal to each other, and the low tides are also roughly equal, the pattern is called a semidiurnal tide. If the two highs and lows differ substantially, the pattern is called a mixed tide. Where there's only one high and one low tide a day, it's called a diurnal tide. One location can experience different tide patterns throughout the month.

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How does SOFAR work? Think of the ocean as consisting of various zones, or layers — sort of like oil and vinegar salad dressing before it’s shaken up—except that ocean layers occur due to differences in salinity (salt content) and temperature variations. Saltier water, and colder water, lie beneath less salty, warmer water.

Because of SOFAR, sound emitted at a certain depth bounces between these various layers and can travel for hundreds of miles. This up-and-down bending of low-frequency soundwaves allows soundwaves to travel great distances without the signal losing significant energy. By placing hydrophones at the axis of the sound channel, researchers can record sounds such as whale calls, earthquakes, and manmade noise occurring vast distances from the hydrophones. In some instances, low-frequency sounds can be heard across entire ocean basins!

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Lagoons are separated from larger bodies of water by sandbars, barrier reefs, coral reefs, or other natural barriers. The word "lagoon" derives from the Italian word laguna, which means "pond" or "lake."

Although lagoons are well defined geographically, the word “lagoon” is sometimes used as a name for a larger region that contains one or more lagoons. For example, Laguna Madre on the Texas Gulf Coast is actually made up of smaller bays and lagoons, while Laguna Beach in Southern California is actually a beach and not a lagoon at all.

There are two types of lagoons: atoll and coastal. Atoll lagoons form when an island completely subsides beneath the water, leaving a ring of coral that continues to grow upwards. At the center of the ring is a body of water that is often deep. The combination of coral growth and water creates a lagoon. It may take as long as 300,000 years for an atoll formation to occur.

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When a storm churns across the ocean, the warm surface waters provide additional moisture and can fuel the storm into a hurricane. As the hurricane grows larger and more potent, it can generate waves as high as 60 feet, tossing and mixing warmer surface waters with the colder, saltier water below. The resulting currents can extend as far as 300 feet/91.5 meters below the surface, wreaking deadly havoc on marine life.

If the wild currents fail to break up coral reefs in their path, the rain-infused water they bring reduces salt levels and otherwise stresses corals. As the hurricane moves toward shore, the underwater tumult can cause shifting sands and muddy shallow waters, blocking the essential sunlight on which corals and other sea creatures rely.

Slow-moving fish and turtles and shellfish beds are often decimated by the rough undercurrents and rapid changes in water temperature and salinity wrought by a hurricane. Sharks, whales, and other large animals swiftly move to calmer waters, however, and, generally speaking, are not overly affected by hurricanes.

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Glass sponges in the class Hexactinellida are animals commonly found in the deep ocean. Their tissues contain glass-like structural particles, called spicules, that are made of silica (hence their name). Some species of glass sponges produce extremely large spicules that fuse together in beautiful patterns to form a “glass house”—a complex skeleton that often remains intact even after the sponge itself dies. The skeleton of the glass sponge, together with various chemicals, provides defense against many predators. Nonetheless, some starfish are known to feed on these rare creatures of the deep.

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"The Bloop" is the given name of a mysterious underwater sound recorded in the 90s. Years later, NOAA scientists discovered that this sound emanated from an iceberg cracking and breaking away from an Antarctic glacier.

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Hurricanes are powerhouse weather events that suck heat from tropical waters to fuel their fury. These violent storms form over the ocean, often beginning as a tropical wave—a low pressure area that moves through the moisture-rich tropics, possibly enhancing shower and thunderstorm activity.

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Just as a microphone collects sound in the air, a hydrophone detects acoustic signals under the water. Most hydrophones are based on a special property of certain ceramics that produces a small electrical current when subjected to changes in underwater pressure. When submerged in the ocean, a ceramic hydrophone produces small-voltage signals over a wide range of frequencies as it is exposed to underwater sounds emanating from any direction.

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Ecoforecasts detail how interactions between organisms and their environment may affect ecological phenomena such as animal extinction, the spread of invasive plants and disease, and the health of waterbodies.

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Wind, tides, and differences in temperature and salinity drive ocean currents. The ocean churns up different types of currents, such as eddies, whirlpools, or deep ocean currents. Larger, sustained currents—the Gulf Stream, for example—go by proper names. Taken together, these larger and more permanent currents make up the systems of currents known as gyres.

There are five major gyres: the North and South Pacific Subtropical Gyres, the North and South Atlantic Subtropical Gyres, and the Indian Ocean Subtropical Gyre.

In some instances, the term “gyre” is used to refer to the collections of plastic waste and other debris found in higher concentrations in certain parts of the ocean. While this use of "gyre" is increasingly common, the term traditionally refers simply to large, rotating ocean currents.

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Given the vast size of the ocean, it is impossible to know the exact number of species that live there. Research suggests, however, that the number of species in the ocean is decreasing. The continued decline in the health of many ecosystems, coupled with rising extinction rates, are likely outpacing species’ ability to evolve to tolerate the conditions of our rapidly changing planet. It is not all bad news, though. Researchers around the world continue to study marine life and habitats to help develop new strategies to preserve vital ocean ecosystems.

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Tides originate in the ocean and progress toward the coastlines, where they appear as the regular rise and fall of the sea surface. Thanks to Sir Isaac Newton’s 1687 discovery, we know that tides are very long-period waves that move through the ocean in response to forces exerted by the moon and sun. However, these gravitational forces do not control when high or low tide events occur. Other forces, more regional than the moon or sun, control the tides. Many of them have to do with the geography and shape of the Earth.

The shape of our planet has a lot to do with differences in gravitational pull at various locations. If Earth was a true sphere covered by an ocean of constant depth, then it would be true that a high tide event would occur at the location with the moon overhead. The tidal "bulge" would move around the Earth with the moon, but this is not the case with our planet. The Earth is not a true sphere, but bulges slightly at the Equator. It is also dotted with large land masses (continents). Areas where the Earth’s surface is higher, such as mountains, have a stronger gravitational force than do places where the surface is lower, such as a valley or cavern. At the same time, the depth of the world ocean varies greatly. All of these factors play into the height of the tides.

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Meteotsunamis are large waves that scientists are just beginning to better understand. Unlike tsunamis triggered by seismic activity, meteotsunamis are driven by air-pressure disturbances often associated with fast-moving weather events, such as severe thunderstorms, squalls, and other storm fronts. The storm generates a wave that moves towards the shore, and is amplified by a shallow continental shelf and inlet, bay, or other coastal feature.

Meteotsunamis have been observed to reach heights of 6 feet or more. They occur in many places around the world, including the Great Lakes, Gulf of Mexico, Atlantic Coast, and the Mediterranean and Adriatic Seas.

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The size of a watershed (also called a drainage basin or catchment) is defined on several scales—referred to as its Hydrologic Unit Codes (HUC)—based on the geography that is most relevant to its specific area. A watershed can be small, such as a modest inland lake or a single county.

Conversely, some watersheds encompass thousands of square miles and may contain streams, rivers, lakes, reservoirs, and underlying groundwater that are hundreds of miles inland. The largest watershed in the United States is the Mississippi River Watershed, which drains 2,981,076 square kilometers from all or parts of 31 U.S. states and two Canadian provinces stretching from the Rockies to the Appalachians!

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NOAA's Center for Operational Oceanographic Products and Services provides tidal current predictions to commercial and recreational mariners who rely on this information for safe navigation. In order to provide the most accurate predictions possible, NOAA must periodically resurvey various coastal and estuarine locations. Survey locations are selected based on mariners' navigation needs, oceanographic analyses, and the amount of time that has passed since the last survey. Given modern improvements in measurement and computing technology, these surveys greatly improve the accuracy of tidal predictions. In 2017, for example, NOAA concluded a three-year current survey of Puget Sound, Washington, to update the region's tidal current predictions. Prior to the survey, predictions were based on limited amounts of data collected in the 1930s-1960s.

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Backscatter is the reflection of a signal (such as sound waves or light) back in the direction from where it originated. Backscatter is commonly used in medical ultrasounds to understand characteristics of the human body, but in the world of hydrography and marine science, backscatter from soundwaves helps us understand characteristics of the seafloor.

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As sea level rises, more and more saltwater encroaches on the land. Along the world’s coasts and estuaries, invading seawater advances and overtakes the fresh water that deciduous trees rely upon for sustenance. The salty water slowly poisons living trees, leaving a haunted ghost forest of dead and dying timber. Still standing in or near brackish water, the decaying trees of a ghost forest resemble giant graying pillars that protrude into the air.

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Rivers flowing over Earth’s gorges create waterfalls that are natural wonders, drawing millions of visitors to their breathtaking beauty, grandeur, and power. But no waterfall is larger or more powerful than those that lie beneath the ocean, cascading over immense cataracts hidden from our view.

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Eutrophication is a big word that describes a big problem in the nation's estuaries. Harmful algal blooms, dead zones, and fish kills are the results of a process called eutrophication—which begins with the increased load of nutrients to estuaries and coastal waters.

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High tide flooding—flooding that leads to public inconveniences such as road closures—is increasingly common as coastal sea levels rise.

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Sand is the end product of many things, including decomposed rocks, organic by-products, and even parrotfish poop.

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Our ocean and coasts affect us all—even those of us who don't live near the shoreline. Consider the economy. Through the fishing and boating industry, tourism and recreation, and ocean transport, one in six U.S. jobs is marine-related. Coastal and marine waters support over 28 million jobs. U.S. consumers spend over $55 billion annually for fishery products. Then there's travel and tourism. Our beaches are a top destination, attracting about 90 million people a year. Our coastal areas generate 85 percent of all U.S. tourism revenues. And let's not forget about the Great Lakes—these vast bodies of water supply more than 40 million people with drinking water. Our ocean, coasts, and Great Lakes serve other critical needs, too—needs that are harder to measure, but no less important—such as climate regulation, nutrient recycling, and maritime heritage. Last but not least, a healthy ocean and coasts provide us with resources we rely on every day, ranging from food, to medicines, to compounds that make our peanut butter easier to spread! So what does all of this have to do with human health?

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Oceanic and atmospheric Rossby waves — also known as planetary waves — naturally occur largely due to the Earth's rotation. These waves affect the planet's weather and climate. Waves in the ocean come in many different shapes and sizes. Slow-moving oceanic Rossby waves are are fundamentally different from ocean surface waves. Unlike waves that break along the shore, Rossby waves are huge, undulating movements of the ocean that stretch horizontally across the planet for hundreds of kilometers in a westward direction. They are so large and massive that they can change Earth's climate conditions. Along with rising sea levels, King Tides, and the effects of El Niño, oceanic Rossby waves contribute to high tides and coastal flooding in some regions of the world.

About this image: Rossby waves naturally occur in rotating fluids. Within the Earth's ocean and atmosphere, these planetary waves play a significant role in shaping weather. This animation from NASA's Goddard Space Flight Center shows both long and short atmospheric waves as indicated by the jet stream. The colors represent the speed of the wind ranging from slowest (light blue colors) to fastest (dark red).

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The world ocean provides so many benefits. Here are ten things the ocean does for humans and the planet:

- The air we breathe: The ocean produces over half of the world's oxygen and absorbs 50 times more carbon dioxide than our atmosphere.
- Climate regulation: Covering 70 percent of the Earth's surface, the ocean transports heat from the equator to the poles, regulating our climate and weather patterns.
- Transportation: Seventy-six percent of all U.S. trade involves some form of marine transportation.
- Recreation: From fishing to boating to kayaking and whale watching, the ocean provides us with many unique activities.
- Economic benefits: The U.S. ocean economy produces $282 billion in goods and services and ocean-dependant businesses employ almost three million people.
- Food: The ocean provides more than just seafood; ingredients from the sea are found in suprising foods such as peanut butter and soymilk.
- Medicine: Many medicinal products come from the ocean, including ingredients that help fight cancer, athritis, Alzheimer's disease, and heart disease.

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In 1513, Spanish explorer Ponce de León sailed into the strong currents of the Florida Straits. Little did he know that within a few years, these uncharted waters, which fed into the Gulf Stream, would become a major international shipping route to and from Europe and the New World.

As Europeans explored and colonized the Americas, they took advantage of the Florida Straits' winds and currents. The winds changed direction often, however, easily pounding countless vessels against miles of treacherous submerged coral reefs off the southern Florida coast.

By 1852, Lieutenant James B. Totten, the U.S. Army's assistant to the Coast Survey, had installed 15 wooden signal poles in the reefs to create more accurate charts of the Florida Keys. Local mariners quickly recognized that the poles themselves helped them safely navigate the reefs, and by 1855, Totten and his team installed a second generation of 16 poles using a more permanent material—iron. The "beacons" each displayed a letter, starting with "A" and ending with "P." Today, remnants of Totten Beacons are protected as historical resources by the Florida Keys National Marine Sanctuary (FKNMS).

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A tide gauge, which is one component of a modern water level monitoring station, is fitted with sensors that continuously record the height of the surrounding water level. This data is critical for many coastal activities, including safe navigation, sound engineering, and habitat restoration and preservation.

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The cerebral-looking organisms known as brain corals do not have brains, but they can grow six feet tall and live for up to 900 years! Found in the Caribbean, Atlantic, and Pacific Oceans, brain corals display what is known as Meandroid tissue integration. This means that the polyps, which are the basic living unit of corals, are highly associated to one another. Their tissues are more closely connected than those of other corals and are not separated by skeletal structures. Many researchers think that the more integrated a coral's polyp tissue is, the more advanced the coral species.

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Not to be confused with a dumping ground or heavily trashed public beach, a catcher beach typically receives its accumulations of debris due to its shape and location in combination with high-energy waves, storms, or winds. Awareness and common knowledge of these types of areas vary significantly by state, although many states have a good understanding of where catcher beaches are located. In many cases, catcher beaches are found in remote areas that are difficult to access and can be challenging in terms of debris cleanup and removal.

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A King Tide is a non-scientific term people often use to describe exceptionally high tides. Tides are long-period waves that roll around the planet as the ocean is "pulled" back and forth by the gravitational pull of the moon and the sun as these bodies interact with the Earth in their monthly and yearly orbits. Higher than normal tides typically occur during a new or full moon and when the Earth is at its perigee, or during specific seasons around the country

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NOAA's nowCOAST is a GIS-based webmap service that provides frequently updated ocean observations along with coastal and marine weather forecasts 24 hours a day. The free online map offers point-and-click access to 60 NOAA data products and services all in one place. With nowCOAST, you can get a one-stop-shop look at coastal conditions — real-time and forecast — before you do or plan anything on the water.

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Clocked at speeds in excess of 68 mph, some experts consider the sailfish the fastest fish in the world ocean. Easily recognized, sailfish are named for the spectacular sail-like dorsal fin that extends for nearly the entire length of their silver-blue body. Additionally, the sailfish's upper jaw is far longer than its lower jaw, forming a distinctive bill that looks like—and sometimes acts like—a spear.

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Sea ice is frozen water that forms, expands, and melts in the ocean. It is different from icebergs, glaciers, ice sheets, and ice shelves, which originate on land. For the most part, sea ice expands during winter months and melts during summer months, but in certain regions, some sea ice remains year-round. About 15 percent of the world's oceans are covered by sea ice during part of the year.

While sea ice exists primarily in the polar regions, it influences the global climate. The bright surface of sea ice reflects a lot of sunlight out into the atmosphere and, importantly, back into space. Because this solar energy "bounces back" and is not absorbed into the ocean, temperatures nearer the poles remain cool relative to the equator.

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In most species, gender is determined during fertilization. However, the sex of most turtles, alligators, and crocodiles is determined after fertilization. The temperature of the developing eggs is what decides whether the offspring will be male or female. This is called temperature-dependent sex determination, or TSD.

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Scientists now believe that some corals can live for up to 5,000 years, making them the longest living animals on Earth.

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During the Age of Sail (circa 15th to 19th centuries), these strong prevailing winds propelled ships across the Pacific, often at breakneck speed. Nevertheless, sailing west into heavy seas and strong headwinds could take weeks, especially around Cape Horn at the southern tip of South America, making it one of the most treacherous sailing passages in the world. The Roaring Forties take shape as warm air near the equator rises and moves toward the poles. Warm air moving poleward (on both sides of the equator) is the result of nature trying to reduce the temperature difference between the equator and at the poles created by uneven heating from the sun.

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Not all fish are cold-blooded. In 2015, researchers with the NOAA Southwest Fisheries Science Center revealed the opah, or moonfish, as the first fully warm-blooded fish. Although not as warm as mammals and birds, the opah circulates heated blood throughout its body, giving it a competitive advantage in the cold ocean depths from 150 to 1,300 feet below the surface.

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Atmospheric rivers are narrow regions in the atmosphere that transport much of the moisture from the tropics to northern latitudes. Atmospheric rivers are part of the Earth's ocean water cycle, and are tied closely to both water supply and flood risks.

A well-known example of a strong atmospheric river is called the "Pineapple Express" because moisture builds up in the tropical Pacific around Hawaii and can wallop the U.S. West Coast with heavy rainfall.

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Have you ever wondered how fish survive in cold winter weather, or where they go when lakes and ponds freeze over? Like many people, fish tend to be less active in the cold. As cold-blooded creatures, their metabolism dips when temperatures take a dive.

The layer of ice that forms on top of a lake, pond, river, or stream provides some insulation that helps the waterbody retain its heat. Because warm water sinks, freshwater fish often gather in groups near the bottom. Some species, like koi and gobies, may burrow into soft sediments and go dormant like frogs and other amphibians, but most fish simply school in the deepest pools and take a "winter rest."

In this resting state, fishes' hearts slow down, their needs for food and oxygen decrease, and they move about very little. If you've ever gone ice fishing, you know that a long line, a slow, colorful lure, and a hearty portion of patience are often required to land this quiet quarry! Popular ice-fishing species include walleye, northern pike, yellow perch, and rainbow trout.

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Ocean noise refers to sounds made by human activities that can interfere with or obscure the ability of marine animals to hear natural sounds in the ocean. Many marine organisms rely on their ability to hear for their survival. Sound is the most efficient means of communication underwater and is the primary way that many marine species gather and understand information about their environment. Many aquatic animals use sound to find prey, locate mates and offspring, avoid predators, guide their navigation and locate habitat, and listen and communicate with each other.

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Known to sailors around the world, the trade winds and associated ocean currents helped early sailing ships from European and African ports make their journeys to the Americas. Likewise, the trade winds also drive sailing vessels from the Americas toward Asia. Even now, commercial ships use "the trades" and the currents the winds produce to hasten their oceanic voyages.

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Satellites are amazing tools for observing the Earth and the big blue ocean that covers more than 70 percent of our planet. By remotely sensing from their orbits high above the Earth, satellites provide us much more information than would be possible to obtain solely from the surface.

Using satellites, NOAA researchers closely study the ocean. Information gathered by satellites can tell us about ocean bathymetry, sea surface temperature, ocean color, coral reefs, and sea and lake ice. Scientists also use data collection systems on satellites to relay signals from transmitters on the ground to researchers in the field—used in applications such as measuring tidal heights and the migration of whales. Transmitters on satellites also relay position information from emergency beacons to help save lives when people are in distress on boats, airplanes, or in remote areas.

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Among the most primitive of all vertebrate species, the sea lamprey is a parasitic fish native to the northern and western Atlantic Ocean. Due to their similar body shapes, lampreys have sometimes inaccurately been called "lamprey eels," but they are actually more closely related to sharks!

Unlike "bony" fishes like trout, cod, and herring, lampreys lack scales, fins, and gill covers. Like sharks, their skeletons are made of cartilage. They breathe through a distinctive row of seven pairs of tiny gill openings located behind their mouths and eyes.

But the anatomical trait that makes the sea lamprey an efficient killer of lake trout and other bony fishes is its disc-shaped, suction-cup mouth, ringed with sharp, horny teeth, with which it latches on to an unfortunate fish. The lamprey then uses its rough tongue to rasp away the fish's flesh so it can feed on its host's blood and body fluids. One lamprey kills about 40 pounds of fish every year.
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Did you know that naturally occurring oil seeps from the seafloor are the largest source of oil entering the world ocean? In fact, they account for nearly half of the oil released into the ocean environment every year. Seeps occur when crude oil leaks from fractures in the seafloor or rises up through seafloor sediments, in much the same way that a freshwater spring brings water to the surface. The waters off of Southern California are home to hundreds of naturally occurring oil and natural gas seeps.

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Once a year, on cues from the lunar cycle and the water temperature, entire colonies of coral reefs simultaneously release their tiny eggs and sperm, called gametes, into the ocean. The phenomenon brings to mind an underwater blizzard with billions of colorful flakes cascading in white, yellow, red, and orange.

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Sea surface temperature provides fundamental information on the global climate system. Because the ocean covers 71 percent of Earth's surface, scientists record sea surface temperature (SST) to understand how the ocean communicates with Earth's atmosphere. SST provides fundamental information on the global climate system. SST is an essential parameter in weather prediction and atmospheric model simulations, and is also important for the study of marine ecosystems.

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Global sea level trends and relative sea level trends are different measurements. Just as the surface of the Earth is not flat, the surface of the ocean is also not flat — in other words, the sea surface is not changing at the same rate at all points around the globe. Sea level rise at specific locations may be more or less than the global average due to many local factors: subsidence, ocean currents, variations in land height, and whether the land is still rebounding from the compressive weight of Ice Age glaciers.

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Marine telemetry interprets into data the movements and behavior of animals as they move through oceans, coastal rivers, estuaries, and the Great Lakes. Telemetry devices, called tags, are affixed to a wide range of marine species, from tiny salmon smolts to giant 150-ton whales. Tags are attached to the outside of an animal with clips, straps, or glue, and are sometimes surgically inserted in an animal's body.

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Known to sailors around the world as the doldrums, the Inter-Tropical Convergence Zone, (ITCZ, pronounced and sometimes referred to as the “itch”), is a belt around the Earth extending approximately five degrees north and south of the equator. Here, the prevailing trade winds of the northern hemisphere blow to the southwest and collide with the southern hemisphere’s driving northeast trade winds.

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A beach advisory leaves it up to users as to whether they wish to risk going into the water. In the case of a beach closure, the state and/or local government decides that water conditions are unsafe for swimmers and other users.

How can beach-goers avoid the disappointment of arriving at their summer vacation destination only to find that authorities advise them not to swim there or that the beaches are closed altogether?

Unfortunately, there is no central database that provides information on beach closures and advisories in real time. The best way to find information on the current water quality of a particular beach is to plan ahead.

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Plastic is the most prevalent type of marine debris found in our ocean and Great Lakes. Plastic debris can come in all shapes and sizes, but those that are less than five millimeters in length (or about the size of a sesame seed) are called “microplastics.”

As an emerging field of study, not a lot is known about microplastics and their impacts yet. The NOAA Marine Debris Program is leading efforts within NOAA to research this topic. Standardized field methods for collecting sediment, sand, and surface-water microplastic samples have been developed and continue to undergo testing. Eventually, field and laboratory protocols will allow for global comparisons of the amount of microplastics released into the environment, which is the first step in determining the final distribution, impacts, and fate of this debris.

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Impacts from land-based sources of pollution—including coastal development, deforestation, agricultural runoff, and oil and chemical spills—can impede coral growth and reproduction, disrupt overall ecological function, and cause disease and mortality in sensitive species. It is now well accepted that many serious coral reef ecosystem stressors originate from land-based sources, most notably toxicants, sediments, and nutrients.

Within the U.S., there are numerous locations where coral reef ecosystems are highly impacted by watershed alteration, runoff, and coastal development. On U.S. islands in the Pacific and Caribbean, significant changes in the drainage basins due to agriculture, deforestation, grazing of feral animals, fires, road building, and urbanization have increased the volume of land-based pollution released to adjacent coral reef ecosystems.

Many of these issues are made worse because of the geographic and climatic characteristics found in tropical island areas. Together they create unique management challenges.

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Climate change and ocean acidification can result in mass coral bleaching events, increased susceptibility to disease, slower growth and reproductive rates, and degraded reef structure.

There are no quick fixes when it comes to a changing climate. In the long term, coral reefs around the world will benefit the most from the reduction of greenhouse gases. In the short term, we can improve coral reef resilience by addressing local stressors, like runoff from land-based sources of pollution and overharvesting of fish.

NOAA’s Coral Reef Conservation Program is helping local managers and communities do just that. The idea is simple. We know climate change is the single greatest global threat to coral reefs. Promoting reef resilience is a local solution. A resilient coral reef is one that can either resist a large-scale stressful event or recover from it. For this to happen, local threats must be kept to a minimum to reduce stress and improve overall reef condition. Scientists are also honing ways to evaluate how resilient a coral reef ecosystem is so that managers can take targeted actions that have the greatest impact.

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Coral reef ecosystems support important commercial, recreational, and subsistence fishery resources in the U.S and its territories. Fishing also plays a central social and cultural role in many island and coastal communities, where it is often a critical source of food and income.

The impacts from unsustainable fishing on coral reef areas can lead to the depletion of key reef species in many locations. Such losses often have a ripple effect, not just on the coral reef ecosystems themselves, but also on the local economies that depend on them. Additionally, certain types of fishing gear can inflict serious physical damage to coral reefs, seagrass beds, and other important marine habitats.

Coral reef fisheries, though often relatively small in scale, may have disproportionately large impacts on the ecosystem if conducted unsustainably. Rapid human population growth, increased demand, use of more efficient fishery technologies, and inadequate management and enforcement have led to the depletion of key reef species and habitat damage in many locations.

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Climate change is the greatest global threat to coral reef ecosystems. Scientific evidence now clearly indicates that the Earth's atmosphere and ocean are warming, and that these changes are primarily due to greenhouse gases derived from human activities.

As temperatures rise, mass coral bleaching events and infectious disease outbreaks are becoming more frequent. Additionally, carbon dioxide absorbed into the ocean from the atmosphere has already begun to reduce calcification rates in reef-building and reef-associated organisms by altering seawater chemistry through decreases in pH. This process is called ocean acidification.

Climate change will affect coral reef ecosystems, through sea level rise, changes to the frequency and intensity of tropical storms, and altered ocean circulation patterns. When combined, all of these impacts dramatically alter ecosystem function, as well as the goods and services coral reef ecosystems provide to people around the globe.

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In summertime when the weather is warm, pregnant female sea turtles return to the beaches where they themselves hatched years before. They swim through the crashing surf and crawl up the beach searching for a nesting spot above the high water mark. Using her back flippers, the reptile digs a nest in the sand. Digging the nest and laying her eggs usually takes from one to three hours, after which the mother turtle slowly drags herself back to the ocean.

The sea turtle lays up to 100 eggs, which incubate in the warm sand for about 60 days. The temperature of the sand determines the genders of baby sea turtles, with cooler sand producing more males and warmer sand producing more females. The phenomenon is called Temperature-Dependent Sex Determination, or TSD, and governs the genders of other reptiles, too, including alligators and crocodiles. Current NOAA research suggests that warming trends due to climate change may cause a higher ratio of female sea turtles, potentially affecting genetic diversity.

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Wildlife viewing is a popular recreation activity, but it is important to know how to interact with ocean wildlife so that you can make the right decisions. Irresponsible human behavior can disturb animals, destroy important habitats, and even result in injury to animals and people.

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Mount Everest, located in Nepal and Tibet, is usually said to be the highest mountain on Earth. Reaching 29,029 feet at its summit, Everest is indeed the highest point above global mean sea level—the average level for the ocean surface from which elevations are measured. But the summit of Mt. Everest is not the farthest point from Earth’s center.

Earth is not a perfect sphere, but is a bit thicker at the Equator due to the centrifugal force created by the planet’s constant rotation. Because of this, the highest point above Earth’s center is the peak of Ecuador’s Mount Chimborazo, located just one degree south of the Equator where Earth’s bulge is greatest. The summit of Chimborazo is 20,564 feet above sea level. However, due to the Earth’s bulge, the summit of Chimborazo is over 6,560 feet farther from the center of the Earth than Everest’s peak. That makes Chimborazo the closest point on Earth to the stars.

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Living shorelines are a green infrastructure technique using native vegetation alone or in combination with offshore sills to stabilize the shoreline. Living shorelines provide a natural alternative to ‘hard’ shoreline stabilization methods like stone sills or bulkheads, and provide numerous benefits including nutrient pollution remediation, essential fish habitat provision, and buffering of shoreline from waves and storms. Living shorelines are known to store carbon (known as carbon sequestration), which keeps carbon out of the atmosphere. Continued use of this approach to coastal resilience will result in increased carbon sequestration and storage, potentially mitigating the effects of climate change.

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During the threat of an oil spill, responders need to know where that spilled oil will go in order to protect shorelines with containment boom, stage cleanup equipment, or close areas for fishing and boating. In order to answer these questions, NOAA oceanographers use specialized computer models to predict the movement of spilled oil on the water surface. They predict where the oil is most likely to go and how soon it may arrive there. During a major spill response, trajectory maps are created to show predictions for the path of spilled oil.

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Pocosins are generally found along the Atlantic coastal plain of the United States, from southern Virginia to northern Florida. These areas typically occur in broad, low-lying shallow basins that do not drain naturally. Pocosins are formed by the accumulation of organic matter, resembling black muck, which builds up over thousands of years. This accumulation of material causes the soil to be highly acidic and nutrient-deficient.

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Of the more than 1,400 species of barnacles found in the world’s waterways, the most common ones are called "acorn barnacles." As anyone who’s ever maintained a vessel knows, removing barnacles requires some elbow grease (or a pressure washer). That's why some boaters call them by their slang name: "crusty foulers."

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For thousands of years, humans found their way by looking to the sky. Sailors used the constellations, sun, and moon to navigate to distant shores. Today, all that's needed is a device called a GPS receiver. GPS stands for Global Positioning System, and it lets us know where we are and where we are going anywhere on Earth.

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The Great Loop is a continuous waterway that recreational mariners can travel that includes part of the Atlantic, Gulf Intracoastal Waterways, the Great Lakes, Canadian Heritage Canals, and the inland rivers of America's heartland. Anyone who completes the journey is then named an official 'Looper.'

For a safe and enjoyable trip, there are a few things to consider when traveling the Great Loop—a great amount of time, a boat with less than a five foot draft to travel inland waterways, NOAA nautical charts, and a NOAA radio. Along the way, it is possible to visit a number of national marine sanctuaries and estuarine research reserves.

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Most people would say that icebergs are white—and most of them are. But did you know that icebergs can also appear in spectacular shades of blue and green? An iceberg looks white because compressed snow on its surface contains large numbers of tiny air bubbles and crystal edges that equally reflect all wavelengths of visible light.

As more and more heavy snow accumulates atop an iceberg, the air bubbles get compressed, forcing the smaller ice crystals to grow together and merge into larger grains. When the iceberg is underwater, the air bubbles are squeezed out and washed away. Then, when light encounters the dense, compressed ice, much of the light penetrates it. The ice absorbs longer wavelengths of colors, such as red and yellow. Colors of shorter wavelengths, like green and blue, reflect the light. This "leftover" blue-green light is what gives some icebergs their remarkable colors.

Additionally, algae often grow on the underwater sides of icebergs, producing beautiful green stripes in the ice. These are readily seen when an iceberg rolls over and sections that were previously underwater are exposed.

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Marine biogeography is the study of marine species, the geographic distribution of their habitats, and the relationships between living organisms and the environment. By mapping benthic habitats, studying what occurs on the bottom of a body of water, and assessing the relationships between the environment and the organisms that live there, biogeographers provide useful information to protect and conserve marine resources.

Marine biogeographers often use Geographic Information Systems, or GIS, to aid in their research of marine animals, plants, and habitats. Scientists and GIS specialists develop map-based data that describe the distribution and ecology of living marine resources and their connections to human communities. State and federal planners can apply these tools and information to position aquaculture sites and alternative energy facilities, and to protect fisheries and coral spawning areas. Information from biogeographers allows planners to consider possible scenarios, such as new development, that may, or may not, impact the environment.

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Forchhammer put the samples through a detailed series of chemical analyses and found that the proportions of the major salts in seawater stay about the same everywhere. This constant ratio is known as Forchhammer's Principle, or the Principle of Constant Proportions. In addition to this principal, Forchhammer is credited with defining the term salinity to mean the concentration of major salts in seawater.

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The vampire squid is a small ( 12-inch-long ) cephalopod found in deep temperate and tropical seas. Originally thought to be an octopus because it lacks the two long tentacles that usually extend past a squid’s eight arms, the vampire squid possesses characteristics of both squid and octopi, and occupies its own order in taxonomy (scientific classification).

On the freshwater side, the vampire fish is a nickname for the payara, an abundant gamefish found in the Amazon Basin. While this large, 1.5-to-3 feet, fish does not suck the blood of its prey, its six-inch-long fangs, which protrude from an undershot jaw, result in a face only a (payara) mother could love.

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For more than 30 years, NOAA's Office of Response and Restoration has played a leading role in the evolving science of hazardous materials (also known as "HAZMAT") spill response. Check out our collection of THREE infographics for a clear explanation of this always complex process.

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Maritime forests are shoreline estuaries along coastal barrier islands that are relatively pristine and support a great diversity of plants and animals. Maritime forests remain largely untouched by commercial development and closely resemble the woodlands where Native Americans inhabited and early settlers settled hundreds of years ago. Trees, bushes, and other plants in maritime forests and estuaries withstand strong winds, periodic flooding, and salt spray. Many species of mammals and reptiles make the forests their home and thousands of birds migrate to maritime forests each year.

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HAZMAT is an abbreviation for "hazardous materials."

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An ocean glider is an autonomous underwater vehicle used to collect ocean data.

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Glacial isostatic adjustment is the ongoing movement of land once burdened by ice-age glaciers.

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NOAA monitors water levels in the U.S. with the National Water Level Observation Network.

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The high winds, heavy rains, storm surge, and flooding associated with natural disasters can pull large structures and other articles into surrounding waters.

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The "marsh organ" is a simple instrument that helps scientists study sea-level rise.

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The nautilus is a mollusk that uses jet propulsion to roam the ocean deep.

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The platypus is a remarkable mammal found only in Australia.

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Once oyster larvae permanently attach to a surface, they are known as spat.

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A turbidity current is a rapid, downhill flow of water caused by increased density due to high amounts of sediment.

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Geocaching is an outdoor treasure-hunting activity that uses GPS-enabled devices.

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GIS is a computer system that captures, stores, checks, and displays information related to positions on Earth’s surface.

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The Census of Marine Life was an international project that recorded the diversity, distribution, and abundance of life in the ocean.

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Aquaculture is the breeding, rearing, and harvesting of fish, shellfish, plants, algae and other organisms in all types of water environments.

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Mesophotic coral ecosystems exist in low light—"meso" means middle and "photic" refers to light.

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Waves are created by energy passing through water, causing it to move in a circular motion.

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An Operational Forecast System provides a nowcast and forecast of oceanographic conditions.

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The distance that sound travels in the ocean varies greatly, depending primarily upon water temperature and pressure.

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While most fish rest by reducing their activity and metabolism, fish "sleep" is different from that of land mammals.

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Blue carbon is a term used to described the carbon captured by the world's ocean and coastal ecosystems.
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PORTS® stands for Physical Oceanographic Real Time System. NOAA PORTS® is an information system that measures and disseminates the oceanographic and meteorological data that mariners need to navigate safely.

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High tide flooding, sometimes referred to as "nuisance" flooding, is flooding that leads to public inconveniences such as road closures. It is increasingly common as coastal sea levels rise.

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Tectonic shift is the movement of the plates that make up Earth’s crust.

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Dead whales, or whale falls, provide years to decades of nutrients for deepwater creatures.

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The horse latitudes are regions of the subtropics characterized by calm winds and little precipitation.
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Horseshoe crabs are "living fossils" more closely related to spiders and scorpions than they are to crabs. .

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The first Earth Day took place on April 22, 1970.

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Pelagic fish inhabit the water column (not near the bottom or the shore) of coasts, open oceans, and lakes.

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Bombogenesis is a popular term that describes a midlatitude cyclone that rapidly intensifies.

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Geodesists measure and monitor the Earth’s size and shape, geodynamic phenomena (e.g., tides and polar motion), and gravity field to determine the exact coordinates of any point on Earth and how that point will move over time.

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The International Date Line serves as the "line of demarcation" between two consecutive calendar dates.

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Scientists agree that the bowhead whale has the longest lifespan of all marine mammals.

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An anchialine pool is an enclosed water body or pond with an underground connection to the ocean.

A hurricane watch means that hurricane conditions (sustained winds of 74 mph or higher) are possible within the specified area.

You can't do better than a point in the Pacific Ocean popularly known as 'Point Nemo,' named after the famous submarine sailor from Jules Verne's Twenty Thousand Leagues Under the Sea.

The ESA defines an endangered species as "any species which is in danger of extinction throughout all or a significant portion of its range." Endangered species are automatically protected by prohibitions of several types of "take," including harming, harassing, collecting, or killing, under Section 9 of the ESA. There are some limited exceptions to these rules listed in Section 10 of the ESA. The Kemp's ridley turtle, considered the smallest marine turtle in the world, is listed as an endangered species throughout its range of the Gulf of Mexico and entire U.S. Atlantic seaboard..

Asian tiger shrimp are native to Indo-Pacific, Asian, and Australian waters, but are now found along the southeast and Gulf coasts of the United States. While small numbers of this invasive species have been reported in U.S. waters for over a decade, sightings have notably increased over the past few years.

Sea foam forms in this way -- but on a much grander scale -- when the ocean is agitated by wind and waves. Each coastal region has differing conditions governing the formation of sea foams.

Ocean waters do hold gold – nearly 20 million tons of it. However, if you were hoping make your fortune mining the sea, consider this: Gold in the ocean is so dilute that its concentration is on the order of parts per trillion. Each liter of seawater contains, on average, about 13 billionths of a gram of gold.

Algal blooms occur when colonies of algae—simple ocean plants that live in the sea—grow out of control. While algal blooms come in many colors (and some have no color at all), they are popularly known as 'red tides' because some are deep red in color.

Oil slicks, on the other hand, are simply films of oil floating on top of the water. While some slicks may be a few inches thick, most are thinner than a human hair. They may form naturally, but they are often introduced by man in incidents ranging from refined fuels or crude oil spilled from a ship to larger events such as last year's Deepwater Horizon oil spill. Oil sometimes emulsifies under certain conditions. Emulsified oil is a mixture of oil and water that often resembles chocolate mousse or pudding.

How do you tell the difference? It can be difficult. Even the experts can be fooled, especially when looking at the ocean from an aircraft.

So what are corals, anyway?

The radius at the equator is larger than at the poles due to the long-term effects of the earth's rotation.  And, at a smaller scale, there is topography—mountains have more mass than a valley and thus the pull of gravity is regionally stronger near mountains.

The group'€™s mission began in the 1970s when congress passed a series of acts that protect fisheries, marine mammals, and endangered species. The problem then arose of how to enforce these new laws. Without the fins, scales, and heads attached, it was impossible for NOAA agents to tell if the samples they came across were from regulated species.

La Niña is sometimes referred to as the cold phase of ENSO and El Niño as the warm phase of ENSO. These deviations from normal surface temperatures can have large-scale impacts not only on ocean processes, but also on global weather and climate.

While conditions on the surface of the Earth where humans are happy are likely to be extremely rare outside of our home planet, the range of conditions in which microbes are found on Earth are more likely to be found on other planets and moons.

Benthic habitat maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. The resulting digital map is viewed using geographic information system tools.