Subtitles section Play video Print subtitles You're in a city 10,000 fathoms beneath the sea. It's quite beautiful. Living under the sea isn't just Hollywood fantasy. Requesting landing clearance, over. Can we build an underwater city? Sure. Whether we build them to survive overpopulation or catastrophic climate change, or to help scientists learn more about our planet. It stands to reason that we must push the boundaries of ocean exploration so that we can bring back solutions. The deep sea could teach us about our own origins and if we can learn about how life originated here, we might be able to learn something about how life may have originated elsewhere. We already know more about the surface of the moon than the depths of our oceans. In comparison to going to the moon living underwater is not that complicated. While our relationship with the ocean started tens of thousands of years ago, the technology that enabled humans to explore underwater is relatively recent. In 1943, a French Naval officer called Jacques Cousteau invented the Aqualung, the precursor to scuba. In his 1964 film "World Without Sun" he explored the sea in his two-man submarine, the Diving Saucer. He'd park it in a garage, which was part of his subaquatic village. These men are the first oceanauts. They are going to live down here for a month. His team spent 30 days beneath the waves. These sunken houses permit us to escape many limitations of diving. More habitats followed, built by amateur enthusiasts as well as serious players, such as the U.S. Navy and NASA. The sea was the next frontier to be explored, and there was interest from beyond the scientific community. President Kennedy wrote to the U.S. Senate in 1961: Knowledge of the oceans is more than a matter of curiosity. Our very survival may hinge on it. In the 1950s and '60s, that particular time period, there's a historical context there that makes underwater living particularly desirable. So there are military applications, and this is the birth of the offshore oil industry and various underwater construction projects. And then you also have a third reason, which has perhaps less of an incentive, and that's that marine biology is starting to develop. What indeed are the limits on flesh and blood beneath the waves? Were people looking at the physiological effects on the body, as opposed to say the scientific work that could be done from those depths? So one of the problems in underwater habitats is that you have to change the gas mixture that can be breathed safely at depth. If you just breathe normal air that we breathe here, or if you breathe pure oxygen, it becomes toxic or you get nitrogen narcosis. So they had to combine different types of gas to breathe at pressure, and they were breathing helium mixtures and nitrogen mixtures, which is why when you watch videos with these aquanauts, they always have that high helium voice. Ca va? The seas remain largely unexplored because of the limits of the human body. We can only dive for a few hours. Every breath of compressed air at depth requires decompression after, be it in a chamber, or by slowly rising back up to the surface. Without it, divers can develop decompression sickness, also known as the bends, where nitrogen in your bloodstream begins to bubble, damaging blood vessels and blocking blood flow. It's potentially lethal. So living in an underwater habitat, like Cousteau's aquanauts, the body stays saturated with inert gases, enabling them to dive and work without decompression. If man need not return to the surface periodically, taking a long time to decompress those potentially fatal bubbles within his body, he can be infinitely more productive down below. But one of the problems is that as soon as you have your breathing, you're living in a helium atmosphere, it is not very good for temperature control at all, and if you're living in the ocean, you can imagine it's quite cold. So one of the problems that they had to figure out how to adapt to is that the divers are constantly cold, they're freezing in this helium atmosphere. And then the other problem is that once you're staying at depth for prolonged periods, so unlike a submarine where you can go up, purge the air, and go back down, you have to develop some sort of air circulation system that is purging CO2 constantly. And that only really works well if you can keep the humidity down. If you're living in a metal container under the ocean, it's difficult to keep the humidity down. So controlling all of these atmospheric conditions was one of the really big hurdles for making it safe for people to live at depth. A lot of these habitats came and went in the '60s and '70s. Can you give us some sense of the historical context? In the 1960s and the 1970s, this is when the space race is going on. So there was this analog between the exploration of inner space, the oceans and outer space and already in the U.S., people in government, at NASA and in the Navy were looking ahead to future space exploration missions and thinking that here underwater, we have a perfect analog example where we can already study how crews are gonna behave in isolation in a small space, over long periods of time. So the Cold War is a really important context for understanding this as well. And the Russians were going into space and there were a few Soviet habitats but they never seemed like a viable, real competition to the Americans. So underwater competition between the Americans and the Soviets played out with nuclear submarines but not underwater habitats. Nobody was colonizing the sea floor. I think the technology was proven in the 1960s and '70s but there were other reasons that it wasn't that useful or proved to not be something that was necessary to do for a long period of time. The technology developed that allowed divers to compress on shipboard instead, instead of at depth. It will take two and one half hours for their bodies to be equal to the same pressure they will experience on the ocean floor. So you could be compressed in a compression chamber in a ship, then lowered in a capsule while still under pressure, exit the capsule, work on the oil head rig, get back in the capsule and remain pressurized at the surface. And that technology did develop out of all of these experiments with underwater habitats but it sort of took the underwater habitats out of the equation. Scientists still see value in spending time under the sea. What sort of questions are they trying to answer? My wife is a marine microbiologist, who's actually here if you want to ask her questions about this. Yeah, that'd be great. All right. Hi. Hi. I am a marine microbiologist, mostly focusing on hydrothermal vents, and I've been doing that for a while now. And my advisor, my PhD advisor was the one who first suggested that the origin of life may have been at hydrothermal events. Yeah. That's one of humanity's big questions, I guess. So, you know, do you think those answers could be at the bottom of the sea? We like to think so. The original idea basically was that hydrothermal vents were kind of like a natural laboratory because they're dominated by gradients. So in the middle of a chimney, it's really hot, it's water that can be up to 400 degrees Celsius, and then two feet away, the water's like two degrees Celsius, right? So in between you have every temperature you could possibly want for all kinds of reactions. They're very hard to study because they're at the bottom of the ocean, thousands of meters deep, and we can only really take samples when we can get a ship out there. If you had the opportunity to spend, say a month underwater next to one of these vents, from a scientific angle, would that be helpful? Yeah, so there's, there's two answers there. One is we do use submarines, so I have been there. I've been in Alvin down to these vents and being there in person is amazing because you get a much better sense of what the environment looks like in a three-dimensional way. Just being in that space I just felt like I had a much better sense of what these habitats really look like and how connected they are and whether microbes and ingredients could flow from one vent to the next. The thing that I would really value whether I was present or not is just being able to look at these things longitudinally over time. Understanding how the microbes adapt over time is something we really haven't addressed yet and is something I'm working on right now to try to understand better. So I think there's a lot of value in that. Now, whether I would need to be physically present for that period of time is another question, because I like bathrooms and I like having food and sunlight, so maybe not. We enjoy the adventure of going down there, but in the end, we do want to sleep in a soft bed that's not cold and damp at the end of the day. The underwater habitats of the 20th century have mostly been retired. A couple still remain serving scientists, but a focus on space exploration and the rise of robotic technology has decreased the need for humans to live beneath the waves. But could there be a resurgence? Fabien Cousteau, grandson of Jacques and an aquanaut, explorer and conservationist in his own right, spent 31 days underwater in 2014. Can you give me a sense of the science that can be achieved when you're underwater for extended periods of time? My team and I were able to execute over three years' worth of equivalent science, as opposed to being based from a ship above. And that has a lot to do with the access to the bottom world. By being able to be based out of an underwater habitat, it's a very unique platform, it's a very unique tool. In the case of being saturated, we could dive 10 to 12 hours, each of us, per day to take advantage of that and to be able to do much, much more research in a workday than you can from the surface. Additionally, as a human being, being right on the ocean's final frontier, you're able to do things that simply are not as easily accessible from an ROV or an AUV or a submersible, but there's still a human factor that needs to be integrated into these kinds of exercises. And with Mission 31, we were able to use all sorts of laboratory equipment that normally are relegated to a laboratory on land and bring them back down to the bottom of the sea. Fabien, you're raising money for a new underwater habitat called Proteus. How's it different from the ones before and why do we need it now?