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Portable Inflatable Habitats | some context from 2021

In June–July 1964, Ed Link – businessman, inventor, philanthropist – conducted his second Man-in-the-Sea experiment in the Berry Islands (a chain in the Bahamas) with Robert Sténuit and Jon Lindbergh, one of the sons of Charles Lindbergh. Sténuit and Lindbergh stayed in Link’s SPID habitat (Submersible, Portable, Inflatable Dwelling) for 49 hours underwater at a depth of 432 feet (132 m), breathing a helium-oxygen mixture. Dr. Joseph B. MacInnis participated in this dive as a life support specialist. The SPID, as the name implies, was a portable inflatable habitat, and was among the several projects through the 1960’s and 1970’s aimed at affording more efficient and effective manned diving operations via new techniques in saturation diving out in the deep oilfields, and also serve as proxies for the space race.

Underlying these ambitious initiatives was the shared vision [among many, but not all] of making the technology accessible to diving scientists. Several habitats dedicated to science came and went through that period and into the early 1980’s, with the last standing today being the Aquarius Reef Base, and the Jules Undersea Lodge, both in the Florida Keys. They have much in common – primarily that they are fixed ‘permanent’ structures, meaning that their operations are limited to their current deployment locations. Both are important platforms that remain relevant to afford science and education opportunities related to living beneath the sea.

Saturation diving, all evolving from this golden era of 1960’s and 1970’s, evolved differently to meet the call of industry, with first applications in the offshore oilfields, and then more recently inshore within freshwater aqueducts and other specialized circumstances. This mode of diving involves use of mobile diving bells, often deployed from a ‘saturation vessel/ship’, where the divers remain under pressure in a deck chamber, and transit to/from depth in a bell. This is done for safety reasons and to allow the vessel to remain mobile and transit to the next work location without waiting for the divers to return from lengthy decompression at depth. This mobility is important for cost-effective mobilization, and it’s equally important as a scientist who wants increased capabilities, couple with access to varied geography.

Common to modern saturation diving, and the science habitats, are relative comforts – both allow for a decent meal at the end of the day, a place to catch some sleep, afford some work space, and reasonable atmospheric and environmental regulation to make the uncomfortable stay as comfortable as possible. To accommodate all of this – for days or even weeks – requires lots and lots of topside support and infrastructure. That means it’s an expensive proposition, and the end has to justify the means – it’s costly to keep people living and working underwater. Industry can sustain this if and when the job warrants it, and science struggles.

Ed Link’s SPID always resonated with me – the idea of being portable by making the habitat structure itself a lightweight inflatable shell or envelope, with the balance of equipment required being relatively modular. The herculean effort to spend 49 hours at a depth of 432 feet is unfathomable – that was more than 50 years ago, and not much related has been done since.

Where did it go? Why did it disappear?

Knowing what I know now, I can speculate that a few issues came to play; one being diver comfort at depth, in the cold, and without the support of today’s saturation diving spreads. This is totally understandable. Two being safety – those guys were as out there on their own as you can get which can very quickly turn the stomach of a seasoned 21st century dive safety professional – also very understandable.

Since 1964, portable inflatable habitats were revisited a few times, principally in the cave diving community, as more modernized techniques in ‘technical diving’ allowed ambitious decompression dives to be carried out – from surface to surface. This means ‘saturation’ at depth is avoided and the divers commit to desaturating on the single dive before surfacing. The dives, and the required decompression can be very, very long – even upwards of a full day. With the longest required decompression stops being in the shallows, this became a demonstrated need to revisit portable inflatable habitat technology. Most notably in recent history was Bill Stone’s Wakulla Project. The project used a semi-portable inflatable structure to afford more comfort and control over tedious decompression requirements following very deep and log cave explorations. Similar efforts have taken place since, all principally in caves in large part given that small habitat structures can be wedged into the ceiling of the cave to maintain its position. That raises the biggest challenge with the technology – ballast and anchoring.

In my own work, which is principally in non-cave environments, I’ve realized the depth and duration boundaries that warranted a close look at the need for a decompression habitat, and the value is plain as day. Our first use was in 2012 as a captsone demonstration following several projects to investigate and document mesophotic coral ecosystems in the Bahamas to depths of 120 meters. With support from the National Geographic Society and Subsalve USA, we built up the Gen 1 ‘Ocean Space Habitat’ as a decompression station resting between 20 and 30 feet of water. It stands alone as the only similar deployment in openwater, and got us thinking seriously about full system mobility coupled with the issue of ballast and anchoring. Even a modest sized structure that can accommodate 2 people exerts substantial buoyant force, and this needs to be managed safely. I can only imagine that the SPID team faced similar challenges, albeit in over 400 feet of water.

Through multiple additional deployments for similar purposes, we were able to apply some know-how from the commercial diving sector to work through safe anchoring and rigging strategies. This remains challenging, but is location/environment specific, and can be achieved with nominal investment.

Over the last few years we’ve carefully considered the work from the last half a century, and believe there is a niche emerging to make use of this portable inflatable habitat technology in a more widespread way – this very well may be the ticket to more routinely afford science with the life in the sea capabilities dreamed about so long ago. The sweet spot isn’t ‘saturation’ per se – that requires creature comforts and costly infrastructure. It also is not ‘decompression’ – that’s a need for only the most experienced technical divers. For the average diving scientist or enthusiast, it’s about a newly immersive experience and time in the water.

Deployed in very shallow water, say 20 or 30 feet where no decompression limits are virtually infinite, portable habitats simply provide space – space to work, space to rest, space to interact, space to observe – and afford time. According American Academy of Underwater Sciences (AAUS) statistics, the average scientific dive is about 45 minutes in length. That means that virtually all marine science data and observations, made by divers being there, to-date have been made within these little snapshots of time, and only those fortunate to have deeper pockets have been granted improved access with more sophisticated techniques. By simplifying the application of habitats to shallow water, and leveraging tools and techniques that are familiar, very readily available, and understood in today’s technical diving community, cost effective scientific diving excursions can reach a full day, overnight, or potentially several days with limited infrastructure and overhead costs. It’s not about depth or duration necessarily – it’s about the human value from the immersive experience.

This changes the game.

For perspective, I like the camping analogy – we certainly learn more from an overnight in the woods, than a short walk through the park. Until now, we haven’t had that opportunity, and it’s one that is so very important. Humanizing marine science means that the diver can become a more effective, and important tool for the job…we’ll see things we’ve never seen, have interactions we’ve never had, and catalyze renewed understandings of how ocean systems work – by becoming part of the system. This was very well illustrated by Dr. Tristan Guttridge and James Glancy during their recent work on Andros with hammerhead sharks, which was featured on Shark Week.



Progress means moving forward, and finding then filling the niche. In the case of underwater living for science, it’s taken literally 50 years of very literal ups and downs, but I’m confident that the sweet spot is not ancient history – it’s still in front of us – it’s simple, it’s palatable, it’s affordable, and it’s well within reach – an underwater camping trip.

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