Given my own recent activity in the field of undersea habitation, I’ve received numerous inquiries as to my thoughts on permanent undersea stations, so have taken some time to summarize here. My perspective is a bit cynical, though comes from having developed, operated, and generated intellectual property behind our own habitat technology, while making a fruitful living as a working diver (with 7000+ hours on the bottom) and diving scientist for my entire life.

First – what are we talking about? 

An underwater habitat is popularly considered a large rigid structure affixed to the seafloor which provides a space for human occupancy. A seafloor station of sorts, purported to offer some advantage to humans in their exploration of the ocean realm by allowing long duration occupancy at any given depth from which they might come and go from the outside watery world. For the layperson, it is important to recognize that there are Ambient Pressure Habitats (APHs), and also one-atmosphere habitats (1ATA). The difference between the two is significant. An APH leaves the occupants subject to the outside water pressure, just like going on a SCUBA dive. A 1ATA system eliminates this exposure to pressure, just like going in a submarine.

There have been several proposed APHs in recent years – throughout my entire professional diving career actually – and often proposed by those considered expert enough to mount such a program. There are elaborate and intriguing renderings of these undersea ‘space stations’ flooded throughout the internet, and yet, as of this writing – they do not exist.

Big dreams aside, it comes down to ‘need’ if there will ever be such a platform that is technologically and operationally sustainable, or even only semi-routinely utilized. These are some facts to motivate hopefully thought-provoking discussion:

1. Deep/long duration dives are carried out every day, in present times, using mobile saturation diving techniques. This technique involves the use of a pressurized bell (TUP-transfer under pressure) deployed from a ship, allowing the divers to spend all day working at the given depth, then return to the safety of a pressurized habitat back on the surface aboard the ship. By maintaining the divers at a ‘storage depth’, they can freely spend any needed amount of time at depth, typically for up to about a month at a time.

This technique directly evolved away from the previous habitat push 50 years ago, when the private sector, defense sector, and commercial sectors were seeking to exploit this fascinating concept of living underwater. Among many discoveries was revealing that returning divers to the surface was not incidental given the fundamental need to ‘desaturate’ (or release gasses dissolved into tissues – decompression) which can take numerous days once ‘saturated’. To do this from an ambient pressure habitat (APH) at any modest depth requires the very same mobile saturation diving systems employed routinely today to maintain control over the depressurization rates so people aren’t killed. Lessons have already been learned the hard way. 

There are existing technologies and techniques that allow this controlled decompression while submerged when coupling both 1ATA and APH capabilities. This process is referred to as a ‘lock-out’ and exists within ‘lock-out submarines’. For instance, today, wet divers can exit and re-enter a mobile nuclear submarine for defense purposes. Regardless of where this desaturation or decompression process occurs, the divers still require a mechanism to return to the surface, and then be brought back aboard some type of surface vessel for the transit home – including emergently.

In very shallow water, generally there is no decompression requirement. Jules Undersea Lodge, an APH stationed in the Florida Keys, operates at a very shallow depth, and consequently occupants of the space are free to surface without any significant physiological risk. At moderate depths, such as the Aquarius Reef Base, there is a procedure for decompression within in the habitat, then rapid re-compression before surfacing using SCUBA techniques. Beyond this depth, it is inherently unsafe from an environmental and physiological standpoint to ascend from an APH by simply diving one’s way out while exposed in the water column for what could be more than 24 hours before reaching the surface. Therefore, a pressurized transfer bell is needed, which is the very same system used in mobile saturation diving every day. In the event the desaturation is carried out via a lock-out/lock-in procedure, the transfer would be made via a 1ATA bell or submersible, both requiring substantial topside capabilities for recovery, analogous to launching a small submarine.

This begs the question – if a mobile sat station is required for safe or emergent egress/recovery of saturated persons from an APH, then why leave them on the bottom overnight when they are sleeping, or even alone for days when exposed to potentially serious risks? They can return to the safety of a ship, remaining under pressure, to avoid inclement weather or tend to any health and safety issues in a controlled environment, and head back to depth when ready to perform required tasks. This has been routine practice for multiple decades as the direct evolution away from APHs, and can be repeated almost indefinitely to afford full work days at depth.

Given the saturation diving technique needed to recover occupants from an APH, an APH itself then becomes a liability since the same work tasks can be conducted from the same surface vessel already on station. This liability is a huge added expense to an already effective technique, and with no clear benefit, other than perhaps the excitement of sleeping with the fishes.

Range extensions away from a ‘base’ are something different and falls in line with 1ATA technology capabilities – this is something else altogether subject to separate discussion. However again, 1ATA systems (personal subs or suits) are routinely at work today and can cover massive amounts of geography on a single excursion, thereafter returning to the safety of the surface.

2. We have APHs today that are not used to their fullest capacity – not because there’s anything wrong with them, but because there is not a critical mass of requirements substantiating the need for routine use of the technology in single locations. Those few remaining habitats today represent the end of an important era, which proved hugely valuable – it evolved into mobile saturation diving which has become the mainstay of deep diving intervention for industry globally. From a scientific standpoint, this same mobility is an absolute requirement to maximize diversity of scientific end uses of long periods of time underwater. This is evidenced by the limited (though important) use cases of the Aquarius Reef Base. Scientists will attest to the surrounding areas having become barren, and littered from past experiments – this is from high diver traffic [human impact]. Therefore, we have observed trends in field research making more use of recreational diving tools (SCUBA) to easily visit a wide variety of sites around the world, rather than heavy focus on a single area. There are limitations to this, though will be broadened as ‘technical diving’ is more widely embraced within the science community, either directly or via citizen science partnerships. Also important to note is the divesture of NOAA from Aquarius and related programs. The US government has had interests in ‘manned’ intervention previously through both the Manned Undersea Science and Technology (MUST) and NOAA Undersea Research Program (NURP) – both are long gone. There failed to be a widespread scientific demand substantiating the cost of elaborate and complex wet diving techniques staged at specific labs or stations. I personally watched this program go belly up, having spent considerable time within the NURP system and performing technical diving activities that were exciting, but just didn’t justify massive investments to scale up the capability within the science sector, nor entice strategic industry partnerships that might benefit from the niche capability.

A head scratching fact is that there are far greater diving capabilities within the sport diving sector than within the hands of scientists. This leaves a systemic cultural know-how and regulatory issue preventing science from benefitting from already available techniques that would massively expand ocean data sets. IMHO – added acute complexity and expertise required for APH incurs overhead costs that are just not justified to a community that wants geographic diversity.

3. Seeking mobility, then why not use the above referenced saturation diving systems for science? Two reasons – they are too expensive relative to current science funding allocated to undersea research, and the training requirements rightfully limits the experience to career sat divers. Most scientific divers spend just one to two weeks per year in the field, and at that have difficulties committing to basic proficiency requirements for even shallow dives. Consequently, the personal submarine market has expanded in the last two decades. Personal submarines do not require the extensive infrastructure or training required to employ saturation diving techniques. The occupants are passive guests in the hands of a pilot/operator and can visit the depths for virtually any length of time, and return to surface quickly, without physiological risk. A scientist who isn’t expert in deep diving systems can see these environments firsthand, and then go home, without substantial training beyond a safety briefing. This of course isn’t perfect – while we benefit from the human eye and critical thinking capacity on site, we do not have the dexterity that comes from the human hand. To-date, this degree of spatial manipulation still requires being ‘wet’. Several initiatives have proposed mobile saturation concepts differing from TUP techniques. Just one was SATFADS (Saturation Fly Away Diving System), a US Navy initiative which would cross bridge to support US science interests…it did not materialize to support scientific end-users.

4. This further begs the question – since industry is satisfied with mobile sat, what non-industry related interests might provide sufficient funds to subsidize an undersea base, or even the use of mobile saturation, to afford the human hand? Many think pharmaceuticals. I can say definitively, having placed numerous dozens of biologics within both academic and industry pipelines, that the collection of biologics alone is not a revenue positive undertaking. It’s much like prospecting for gold, except with a 10-20 year net-negative research pipeline prior to any hint of commercialization. Collectors relinquish most of the rights since it’s the laboratory work that scales value. Today, only a speck of tissue is needed for this type of work – that’s a one shot dive in any given area with no need to return, ever, and the follow-on screening or protein expression activities can be carried out in a lab. In large part, the deepwater collecting can be done with a Remotely Operated Vehicles (ROVs), though there are challenges in collection tooling and preservation of tissue in situ. These same tooling issues are present with personal subs. There are significant advantages to a person collecting cryptic specimens, though again, there is presently no requirement to scale this front-end acquisition. Current marine pharmaceutical pipelines are backlogged – there are hundreds, possibly thousands of isolated compounds that warrant additional study – I have a freezer full. Those development pipelines require huge capital infusions, all net negative for a very long period of time. Biological prospecting of novel environments is important, though a tiny element of a very large industry that does not currently practice a circular economy. There is hope that this changes, though is in the hands of global political actions and identifying mechanisms to actually enforce the Nagoya Protocol with traceability of tissue origins.

Other proposed use cases are said to warrant these undersea stations – aquaculture, tourism, education, resource mining, data centers, possibly archaeological investigations. In large part I think it’s becoming obvious that industrialization of the ocean is damaging – oil/gas, now wind, large scale mining, farming, trawling – adding more permanent structures doesn’t help the environmental cause, and none of these sectors has established activities warranting the ‘need’ for adjunct occupied APHs. Well-established techniques are used, routinely, and an APH does not offer a cost advantage to sway industry routines. Today, we have vast arrays of sensor and robotic networks providing information without having to keep a person underwater indefinitely. A single fiber optic strand, thinner than a human hair, allows gigabit level data transmission. Placing expensive production studios, laboratory equipment, or other human operated devices underwater where they are subject to condensate and exponentially increased maintenance costs just isn’t required – it adds unnecessary complexity and therefore expense to achieving the very same objectives.

5. There are often parallels drawn to manned space exploration, implying that living in a subsea station is just like living on the space station. It’s actually very, very different when studying the nuances. Space can be argued as a steppingstone to reach further frontiers, and we need to understand how to operate within that envelope if we are to take those steps – absolutely! Indeed, humanity may have to become a multi-planetary civilization to survive at growing scales. However – we’ve already been to the bottom of the ocean, and we’ve already identified the maximum limits of human physiology [50 years ago]. In fact, the entire field of hyperbaric medicine was an evolution from prior APHs. Today, hyperbaric medicine is carried out in clinical or laboratory settings – we do not need to live at depth to better understand physiology, though those data sets are useful when captured opportunistically. When habitats are used as space analogs today, it’s to study human factors and psychology of confined space living, with the benefit of pseudo weightlessness outside. That’s a useful proxy, but both of those are also routinely studied on land or in test tanks and don’t require tens to hundred-million-dollar investments. Even today, NASA employs the use of the Aquarius Reef Base, in moderately shallow water, only on a sporadic basis to fulfill its requirements of space analog missions.

While huge expanses of the ocean have not been visited by people, we [humanity] already have a full complement of technology platforms at our disposal which can access these areas safely. The outstanding duty we have is to actually put them to work in a meaningful way and make incremental improvements such that they are valuable and viable intervention tools. Many intervention systems sit idle for very long periods of time because of their already significant expense and complexity.

If there’s a ‘need’ for habitation, it comes from a tiny crack in the subsea intervention space where someday it might be more cost effective to stay put and avoid the transit time to/from surface when working on the bottom – this is well outside the capabilities and scope of APHs, and applies uniquely to 1ATA systems. This technology, which spans subs to atmospheric suits to potentially 1ATA habitats, is still in its infancy. Albeit a moon-shot, Phil Nuytten’s 1ATA Vent Base Alpha presented a scenario for mining where a station might be maintained adjacent to a thermal vent with energy harvested from the thermal vent used for sustenance. It’s a thought-provoking concept, and shines light on some realities – autonomy in power generation and regenerable life support are areas requiring strategic investments. Though again, do we ‘need’ it – the miners already do what they do.

There’s a big difference between needs and wants, where needs can benefit from business interests and investments, and wants benefit from philanthropic intent. Ocean interventions require a balance of the two that I don’t believe we have at a broad societal level.

Perhaps, and hopefully, someday.

On the interim – my honest opinion – think top-down, rather than bottom-up, and that will reveal the path to advance human intervention. By that I’m referring [with some bias] to my own work on underwater habitats. We’ve gone down a path in highly portable lightweight habitats that represents an incremental forward extension in the field of ‘technical diving’. These structures allow us to maximize the potential of current wet diving technology used commonplace in the recreational diving sector, namely rebreathers. Since 2012, we’ve taken demonstrable steps to make this a viable concept and have built and deployed multiple systems successfully – allowing full days spent underwater. This is very different than APHs, as they are not used to ‘saturate’ a diver at depth, rather they are used to push a diver’s ceiling (the depth at which they cannot ascend past without physiological detriment) ‘down’. Strategic implementation of this technique allows the well-trained modern diver to spend literally all day underwater within routinely accepted sport diving depths. Multiple days can now be spent underwater without significant expense, afford very long durations all throughout the routinely visited wet diving depths, impose virtually no environmental impact, and cost nil relatively speaking.

The challenge to all those pursuing big habitats – prove that it’s needed – prove that we need a person on the bottom for a full day and need an APH to do it. Outside of industry (who employs mobile saturation diving) if we don’t need a person on the bottom in 60 feet of water for 8 hours, then we certainly don’t need a person on the bottom in 600 feet of water for 8 hours. It’s a very challenging proposition, though demonstration (if needed) does not require 7+ figure investments – we can afford multiple days underwater NOW – where is the need? I don’t have that answer, though assume it will reveal itself in time (on the bottom).