Forty-six hours before Rüdiger Koch officially seized the Guinness World Record for the longest time spent living in an underwater fixed habitat, I took a 15-minute motorboat ride from Linton Bay Marina, in north-central Panama, to visit him. It was a warm afternoon in January, and Koch was approaching a full 120 days spent working, eating, sleeping, drinking and smoking cigars in a room 36 feet below the surface of the Caribbean.

His 304-square-foot habitat was inside the underwater buoyancy chamber that helps stabilize a floating home called SeaPod Alpha Deep. An armed security guard was in the above-water part of the structure, monitoring Koch and ensuring that the pod did not have “any visitors that we don’t want.” When my boat arrived, he threw down a cable and winched me up. Then I made my way down a 63-step spiral staircase to the circular lower chamber — a dizzying process, as the SeaPod rocked in the loudly sloshing sea. I was greeted by a beaming Koch, a bald 59-year-old German engineer with a whitened beard and a Buddha belly.

He gave me a tour, pointing to a school of sardines outside a porthole. The quarters came equipped with a bed, an exercise bike, Starlink internet and a dry toilet. A digital clock on the wall was counting down toward his 120-day goal. (The previous record was 100 days, set in 2023 by Joseph Dituri at Jules’ Undersea Lodge, off the coast of Key Largo, Fla.) “I’ve enjoyed the time, actually,” Koch said in his heavy German accent, his face greenish-blue from the light pouring in. “This is what people get completely wrong. They think that I feel like a prisoner, and I’m putting marks on the wall. My food is excellent, my booze is excellent.” A person came by to clean daily.

Koch arrived here, in small part, via a San Francisco-based nonprofit called the Seasteading Institute, which promotes “living on environmentally restorative floating islands with some degree of political autonomy.” The vision, as the Institute’s president, the “seavangelist” Joe Quirk, once told Guernica, is “startup societies where people could form whatever kind of community they wanted” — a libertarian-inflected world where, it is said, you could “vote with your boat,” relocating to a community in line with your views.

The concept captured people’s imaginations long before it had a name. In 1895, Jules Verne published “Propeller Island,” a novel about a moving man-made island inhabited by millionaires. By the 1960s, real attempts were being made: Ernest Hemingway’s brother, Leicester, founded the Republic of New Atlantis, a bamboo raft anchored about six miles off the coast of Jamaica. (It washed away.) Still extant is the Principality of Sealand, founded in 1967 on a disused antiaircraft platform seven miles off the shore of Britain. The inventor R. Buckminster Fuller helped design a floating metropolis called Tetrahedron City; the project’s financier died, and plans to build it were abandoned.

Koch spent his career in aerospace engineering; he is also a “long-term” believer and investor in Bitcoin. Now his time is occupied by Ocean Builders, the company that has set up three solar-powered SeaPods, of differing designs, near Linton Bay Marina. It is a partnership between Koch and two other independently wealthy men: Chad Elwartowski, an American Bitcoin enthusiast; and Grant Romundt, a Canadian tech entrepreneur on an “anti-aging health-span journey.”

Koch and Elwartowski first connected through a Seasteading Institute-affiliated message board. Ocean Builders stresses that it is not a seasteading project — it offers “eco-forward housing solutions” — but Koch compares the seasteading movement to the American frontier and its “profound effect” on society. “In history lessons, we are learning a lot about the rise of the commoners, like it just happened somehow,” he told me. “But it didn’t happen somehow. It happened because the aristocrats back in Europe, they had to relax things, because otherwise people would just go to the New World.”

Modern society, he said, had turned stagnant. But if living on the sea, or in space, became a realistic option, “then the ruling classes back home have to think about what to do to make their countries more attractive.”

The history of seasteading is littered with cool-looking renderings that never came to be, for places with names like Oceania and New Utopia. “A lot of seasteaders are on Step 0.5: They’re just these guys on group chats thinking, Oh, it’d be so cool if we could live on the ocean,” says the British filmmaker Oswald Horowitz, who is working on a documentary about the Italian businessman Samuele Landi — a fugitive from the law who managed to live for 13 months on an 800-ton deck barge before a rogue wave hit the vessel off the coast of Dubai, killing him.

The Seasteading Institute — founded in 2008 by Wayne Gramlich and Patri Friedman, and kick-started with half a million dollars from the billionaire Peter Thiel — is one of a few organizations hoping to change that. There are those who have criticized the movement’s libertarian bent and called it a vanity project of the rich; Peter Newman, an Australian professor of sustainability, went so far as to describe one proposed project as “apartheid of the worst kind,” a dream in which the wealthy can remove themselves to futuristic ocean villages and “sneer at the rest of the world.” The fact that Thiel, a boogeyman of the left, is so well associated with the idea (despite apparently having cooled on it) is seen as a P.R. headache by companies like Ocean Builders, which sells itself as a lifestyle business, not an ideological project.

In Panama, Elwartowski expressed irritation when Thiel’s name came up in conversation. “He bought himself two decades’ worth of association with seasteading with $500,000,” he said. “I think a lot of these billionaires — like with Musk and Mars — everybody’s got to have this thing associated with them to make them seem interesting.” He pointed out that the SeaPods were registered as houseboats, not the start of some self-governing seastead community. “We’re about as interesting as these sailboats with people living on them on a daily basis,” he said, referring to the surrounding marina. “Nobody’s asking these guys, ‘Where does the poop go?’”

Ocean Builders first made international headlines in 2019, when Elwartowski and his future wife, Nadia, a Thai national, took up part-time residence in a 250-square-foot octagonal pod designed by Koch. (It was named XLII, a reference to the number 42 in Douglas Adams’s “The Hitchhiker’s Guide to the Galaxy.”) The structure was anchored outside Thailand’s territorial waters, just under 14 miles from shore. In an online video documenting the erection of the 65-foot-tall spar that supported the cabin, Elwartowski offered a message: “To all those out there who want to control people’s lives through force, here’s my big finger to you. You know where you can stick this.”

Life seemed blissful for Chad and Nadia in their sea cabin, for a time. “It’s very apparent that the Thai authorities are very lazy, and we would just assume that Thailand is never gonna send anybody that far out,” Chad told me. But this was hubris. Within months, Thai military officials raised national security concerns, accusing the couple of trying to establish an independent state. (“We were not trying to create a nation,” Chad stressed.) The couple were on land in Phuket when they got word that they could be in legal peril. Along with Koch, they fled by sailboat.

Thai officials towed their seastead to shore. As the drama was unfolding, Romundt happened to be attending a conference in Singapore, a country that does not have an extradition agreement with Thailand; he managed to obtain entry paperwork for his friends, hire a speedboat and rush out to their craft just before Singaporean authorities boarded. The Elwartowskis now live in “boring” suburban Indianapolis with their two young children.

The day before I joined Koch under the sea, I took a boat to visit Romundt on SeaPod Alpha Blue, which makes good on the lifestyle-company approach. It combines the charm of an upscale Manhattan condominium with 360-degree views of the bay and surrounding islands. It features a smart bed, a smart shower, a smart toilet and Ocean Builders’ “liquid computer,” a P.C. immersed in nonconductive oil to protect it from the corrosive sea air. You can stream Netflix on a wall-mounted 43-inch TV; when I was there, the company was testing a drone for food deliveries from the marina.

Romundt lives on SeaPod Alpha Blue more or less full time. He doesn’t much care for going to shore, which he does, begrudgingly, via boat pickup or Sea-Doo. “In my opinion, living on land is ghetto,” he joked as he showed me around the gently rocking pod’s 914-square-foot interior. The first SeaPod prototype cost about $6 million to build, he said, but Ocean Builders hoped to get the price as low as $1.2 million.

Romundt, looking youthful in his early 50s, was barefoot, wearing a sleeveless tee and loose cotton-linen pants. He told me about growing up in Toronto, the son of immigrants from Germany and Guyana, a shy kid and unmotivated student whose life would take several colorful turns: running a paragliding business, pursuing recreational salsa dancing, heading up a successful online startup for hairstylists. After years spent suffering from sarcoidosis, a sometimes chronic inflammatory disease, he felt like the end of his life was near, he said. After his realization, he said — tears were now streaming down his face — “every cell in my body came alive and said, ‘I choose to live.’” When his condition improved, he felt he’d been granted a second chance, and was determined to seize it. In 2016, he booked a floating-house Airbnb in a Toronto marina and fell in love with the lifestyle.

We made our way to the roof, where Romundt — a frequent “one meal a day” dieter and longevity-supplement taker — meditates every night. He pointed out Koch’s pod, a mile to the northeast. The company had plans to convert it into a marine-restoration and scientific-study facility. “The way we did things on land, we really screwed up,” he said. “We’re destroying things left and right, and here we have a chance to do it right.”

When I visited Koch, he struck a similarly hopeful tone. “I’m positive about the future,” he said. “This is not stupid [expletive] for a couple of billionaires. This is not an ‘Elysium’ kind of thing.” He was referring to the film, by Neill Blomkamp, in which the 1 percent orbit a ruined Earth in a slick space station. “It can be the reality for all of us.”

Eventually the subject turned to his armed guard upstairs. “This is a dangerous area,” Koch said. He also worried — even in Panama — about the Thai government. In 2023, The Financial Times reported that a “deeply paranoid” Koch had agreed to pay a South African private investigator, Kobus Steyn, the equivalent of $500,000 in crypto to assassinate a Thai naval officer, Sittiporn Maskasem, whom Koch blamed for the impoundment of the earlier seastead. In communications with Steyn, the article reported, “Koch muses on imprisoning, torturing, even executing people who might have stood in the way of his metastasizing desire for revenge.”

When I brought up the article, Koch described Steyn as a “disgruntled” contractor whom he had actually hired to investigate suspected malfeasance by a Thai tanker that he said was in the waters near XLII. I asked him about the hit-man allegations. “What is he supposed to do — kill the Thai government one by one?” Koch replied dryly. “I admit that sometimes I would have liked that,” he added with a laugh. (Later, a representative for Koch “unequivocally” denied that he had ever hired Steyn, or anyone else, for any form of violence or retaliation.) When I contacted Steyn, he said the communications he shared with The Financial Times spoke for themselves, and described Koch as a “dangerous and unstable individual.” “He never hired me as a hit man,” Steyn said via email, then added: “But if he claims he never expected me to act in such a capacity, he is lying.”

Koch admitted that his reported paranoia “was not invented.” At the moment, though, he was in a very good mood. At the height of the pandemic, he, Romundt and Elwartowski purchased a cruise ship at a bargain price, intending to permanently anchor it off the coast of Panama; when costs and maritime regulations led them to abandon that plan, the internet reacted with headlines like “Bitcoin Dudes Buy Cruise Ship for Crypto Utopia, Immediately Bungle Everything.” Minutes before I arrived, Koch told me, he had finally wrapped up legal loose ends related to the ship’s sale. As the conversation wound down, Koch stressed again that he’d had a pleasant stay in his underwater domain. “So I couldn’t go up, and my toilet sucks,” he said. “Other than that, I have no reason to complain.”

Shortly past noon on Friday, Jan. 24, Koch watched intently as the blue LEDs of his countdown clock began to flash a long series of zeros. He raised his fists in triumph and let out a Schwarzenegger-esque holler: “We did it!” He pumped one arm as if he’d just bowled a strike, broke into a laugh and hugged Romundt. Dressed in a promotional polo shirt and jean shorts, he made his way to the upper level of the pod and took a dramatic leap off the side, splashing down in the warm water 17 feet below.

The record, covered by news outlets worldwide, was a P.R. bonanza for Ocean Builders. At a ceremony at the nearby marina, a freshly showered Koch (he had to use a bucket and a washcloth in his underwater room) acknowledged that some people might view what his company was doing as “just the fancy of a few people with too much money at their hands.” But Ocean Builders argues otherwise. Romundt announced that the company had been contracted to build 20 eco-friendly SeaPods to surround a planned floating city in the Maldives; in the rendering, it looks like a Technicolor Venice.

How did it feel, I asked Koch, to emerge from his chamber after 120 days? “It felt like waking up,” he said. “Down there is kind of a dream world.” Nights were simultaneously tranquil and noisy, courtesy of creatures like pistol shrimp, whose claws create loud snapping sounds. “Sometimes I lie awake and just listen,” he said. “The Darwinian drama keeps going on outside.” He paused. “You’re talking to an engineer,” he said. “We probably need to put a poet down there.”

That night, after dinner with friends on shore, Koch took a boat back to SeaPod Alpha Deep. This time, he stayed upstairs.