More than 20ft below the surface of a Florida lagoon, one man is on a mission. Having already broken the record for the longest time living underwater, Dr Joseph Dituri is planning to spend 100 days in his subaquatic compound, to research the effects of hyperbaric pressure on the body. Dituri has now endured two and a half months in the Jules’ Undersea Lodge, at the bottom of a lagoon in Key Largo, Florida, as he attempts to document the long-term effects of increased pressure on the body. In the underwater pod the atmospheric pressure is 70% higher than at the surface, and researchers like Dituri believe this could hold the key to reversing the ageing process and helping people – including himself – live until 110 years old. “I’m not trying to claim that this is gonna keep you immortal,” Dituri said, speaking via Zoom. “But we know that [exposure to increased pressure] increases stem cell proliferation. It increases telomere length, it also increases collagen. So we’re trying to check cellular ageing. Look – I’m 55 years old. I’m only halfway through this thing.” Dituri, a youthful looking quinquagenarian who has shoulder-length hair and a beard, is an enthusiastic interviewee, no more so than when he lifts up his laptop, crawls through the hole that connects one side of the pod from another, and shows off his toilet. It’s a small toilet, the kind you might find in an RV, a long-distance bus, or a low-budget campsite, and is connected to above ground sewage systems. The toilet is getting a lot of use. “I’m at an increased pressure down here,” Dituri said. “So there’s an increased frequency and urgency of urination.” The pressure in the underwater compound is 25lb per square inch, compared with 14.7lb per square inch above water. To paraphrase Dituri, who has a PhD in biomedical engineering, that means things like bladders are getting squeezed more. Dituri’s expedition has loftier goals than urine, however. As a researcher into hyperbaric medicine – “hyper meaning more than, baric meaning pressure” – Dituri said he spends much of his days testing his blood and saliva to observe any changes as a result of his habitat. He has also been subjected to electrocardiograms, which measure the heart’s function, electroencephalograms, which record brain activity, and pulmonary function tests, which assess how the lungs are performing. “We know that hyperbaric pressure increases stem cell proliferation. It increases telomere length, it also increases collagen, and collagen is the building block of every cell in your body,” he said. Telomeres are DNA sequences that tend to shorten over time, which decreases cell production and, essentially, brings about ageing. Increasing the length of those telomeres could reverse that process, while collagen, Dituri said, “is the building block of every cell in your body”. Dituri spent 28 years in the navy, where he was a submersible expert, before turning to academia. He now teaches at the University of South Florida while maintaining a persona as “Dr Deep Sea”, through which he aims to spread enthusiasm for science to children. Although living at the bottom of a lagoon might not be to everyone’s tastes, some futurists have mooted the possibility of underwater cities as a way to deal with overpopulation. A report commissioned by Samsung in 2016 predicted that in a hundred years time underwater cities “are likely to become a reality”. These cities would thrive by “using the water itself to create breathable atmospheres and generating hydrogen fuel through the process”, the report said. A mocked-up image showed a huge see-through ball, housing multi-story buildings and parks. There’s a problem with that, though. Dituri has discovered – he doesn’t go into detail as to how – that the increased pressure means ejaculate travels a much shorter distance than at the surface. “I don’t think you could propagate the species down here,” he said. “I really don’t. And I’m very shallow here. I know you can’t propagate at any deeper.” Propagation aside, there are other drawbacks. In the pod oxygen makes up a greater percentage of the atmosphere, so naked flames are forbidden. Instead Dituri has to cook all his meals – from his Instagram these dishes seem to be mostly egg-based – in a microwave. “The hardest bit of this whole thing is logistics,” Dituri said. His food is delivered by scuba divers, which seems unsustainable, while he is lucky to have plenty of water. As his time underwater has continued, the provision of these resources has got Dituri thinking about how the body, and mind, can perform and survive in isolation – particularly in relation to space travel. By the end of his mission, Dituri will have spent 100 days cocooned in the lagoon, and he suggests that Elon Musk, the eccentric founder of Tesla and the Space X space exploration company, may not have fully thought through his plan to dispatch humans to Mars within the next five to 10 years. The trip to the red planet would require enough food and water for the 200-day journey – and twice as much if Musk decides to bring them back. “What food are people going to eat that’s shelf-stable, non-refrigerated, that’s storable, that tastes good, that’s not going to make us go batty crazy?” Dituri said. But is Dituri ever afraid in the pod? The Jules’ Undersea Lodge now functions as a hotel, as well as a research space, but was built in the 1970s and spent its early years as the La Chalupa research laboratory off the coast of Puerto Rico. It seems as if spending time in a quite small, 50-year-old, windowed capsule, surrounded always by water that is desperate to break in, could occasionally provoke anxiety. Not so. “Afraid of what? There is no 25ft shark that’s coming through that window. That window is four and a half inches thick. I’ve done the math,” Dituri said. “You know, as far as flooding this thing, physics will not allow it unless somebody has a drill and they’re drilling holes in the top of this.” Still, the experiment is not without risks. Dituri is tall, and he keeps whacking his head on the roof of the pod. He also has cut his finger, and due to the 100% humidity in his living quarters, it is yet to heal. Those things aside, Dituri says the data gathered will be worth it. He’s enjoyed speaking to schoolkids too – he has interacted with thousands over Zoom – and hopes to foster enthusiasm for science. “If we can do that, boy we are winning,” he said. “That’s my gig. If we can turn a kid into a little bit more of a scientist, that’s not bad at all.”