Vanguard feels and smells like a new RV. It has long, gray banquettes that convert into bunks, a microwave cleverly hidden under a counter, a functional steel sink with a French press and crockery above. A weird little toilet hides behind a curtain.

But some clues hint that you can’t just fire up Vanguard’s engine and roll off the lot. The least subtle is its door, a massive disc of steel complete with a wheel that spins to lock.

Once it is sealed and moved to its permanent home beneath the waves of the Florida Keys National Marine Sanctuary early next year, Vanguard will be the world’s first new subsea habitat in nearly four decades. Teams of four scientists will live and work on the seabed for a week at a time, entering and leaving the habitat as scuba divers. Their missions could include reef restoration, species surveys, underwater archaeology, or even astronaut training. 

One of Vanguard’s modules, unappetizingly named the “wet porch,” has a permanent opening in the floor (a.k.a. a “moon pool”) that doesn’t flood because Vanguard’s air pressure is matched to the water around it. 

It is this pressurization that makes the habitat so useful. Scuba divers working at its maximum operational depth of 50 meters would typically need to make a lengthy stop on their way back to the surface to avoid decompression sickness. This painful and potentially fatal condition, better known as the bends, develops if divers surface too quickly. A traditional 50-meter dive gives scuba divers only a handful of minutes on the seafloor, and they can make only a couple of such dives a day. With Vanguard’s atmosphere at the same pressure as the water, its aquanauts need to decompress only once, at the end of their stay. They can potentially dive for many hours every day.

That could unlock all kinds of new science and exploration. “More time in the ocean opens a world of possibility, accelerating discoveries, inspiration, solutions,” said Kristen Tertoole, Deep’s chief operating officer, at Vanguard’s unveiling in Miami in October. “The ocean is Earth’s life support system. It regulates our climate, sustains life, and holds mysteries we’ve only begun to explore, but it remains 95% undiscovered.”

Subsea habitats are not a new invention. Jacques Cousteau (naturally) built the first in 1962, although it was only about the size of an elevator. Larger habitats followed in the 1970s and ’80s, maxing out at around the size of Vanguard.

But the technology has come a long way since then. Vanguard uses a tethered connection to a buoy above, known as the “surface expression,” that pipes fresh air and water down to the habitat. It also hosts a diesel generator to power a Starlink internet connection and a tank to hold wastewater. Norman Smith, Deep’s chief technology officer, says the company modeled the most severe hurricanes that Florida expects over the next 20 years and designed the tether to withstand them. Even if the worst happens and the link is broken, Deep says, Vanguard has enough air, water, and energy storage to support its crew for at least 72 hours.

That number came from DNV, an independent classification agency that inspects and certifies all types of marine vessels so that they can get commercial insurance. Vanguard will be the first subsea habitat to get a DNV classification. “That means you have to deal with the rules and all the challenging, frustrating things that come along with it, but it means that on a foundational level, it’s going to be safe,” says Patrick Lahey, founder of Triton Submarines, a manufacturer of classed submersibles.

Although Deep hopes Vanguard itself will enable decades of useful science, its prime function for the company is to prove out technologies for its planned successor, an advanced modular habitat called Sentinel. Sentinel modules will be six meters wide, twice the diameter of Vanguard, complete with sweeping staircases and single-occupant cabins. A small deployment might have a crew of eight, about the same as the International Space Station. A big Sentinel system could house 50, up to 225 meters deep. Deep claims that Sentinel will be launched at some point in 2027.

Ultimately, according to its mission statement, Deep seeks to “make humans aquatic,” an indication that permanent communities are on its long-term road map. 

Deep has not publicly disclosed the identity of its principal funder, but business records in the UK indicate that as of January 31, 2025 a Canadian man, Robert MacGregor, owned at least 75% of its holding company. According to a Reuters investigation, MacGregor was once linked with Craig Steven Wright, a computer scientist who claimed to be Satoshi Nakamoto, as bitcoin’s elusive creator is pseudonymously known. However, Wright’s claims to be Nakamoto later collapsed. 

MacGregor has kept a very low public profile in recent years. When contacted for comment, Deep spokesperson Louise Nash refused to comment on the link with Wright, only to say it was inaccurate, but said: “Robert MacGregor started his career as an IP lawyer in the dot-com era, moving into blockchain technology and has diverse interests including philanthropy, real estate, and now Deep.”

In any case, MacGregor could find keeping that low profile more difficult if Vanguard is successful in reinvigorating ocean science and exploration as the company hopes. The habitat is due to be deployed early next year, following final operational tests at Triton’s facility in Florida. It will welcome its first scientists shortly after. 

“The ocean is not just our resource; it is our responsibility,” says Tertoole. “Deep is more than a single habitat. We are building a full-stack capability for human presence in the ocean.”

Update: We amended the name of Deep’s spokesperson

Like many new nuclear startups, Kairos promises a path to reliable, 24/7 decarbonized power. Unlike most, it already has prototypes under construction and permits for commercial reactors. 

Kairos made last year’s list because of a safer design for small modular reactors that produce power from nuclear fission. The company uses molten salt to cool its reactions and transfer heat, rather than the high-pressure water that’s used in existing fission reactors. The company was moving fast but cautiously, planning a series of non-nuclear prototypes to explore how best to pump this special coolant, a mixture of fluorine, lithium, and beryllium. 

That iterative process continues today, with the recent installation of a non-nuclear reactor vessel for Kairos’s third test unit at the historic Oak Ridge nuclear site in Tennessee. The unit will test the handling of the coolant and the company’s innovative fuel—golfball-sized pebbles that package tiny seeds of uranium within a series of carbon and ceramic shells. This fuel was developed by the United Kingdom and the US Department of Energy (DOE), which has committed up to $303 million to support the construction of a reactor called Hermes, currently underway at the site. 

Ultimately, Kairos expects the combination of its fuel and special coolant to enable commercial reactors that are cost-competitive with natural gas plants and boast safer operation than conventional reactors, even in the event of complete power loss. 

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Key indicators

• Industry: Nuclear power
• Founded: 2016
• Headquarters: Alameda, California, USA
• Notable fact: In 1954, Oak Ridge National Laboratory in the US was home to the first molten salt reactor, an experimental power source for a possible supersonic nuclear aircraft.

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Potential for impact

With sharp cuts to US federal funding for solar and wind projects, nuclear power is one of the few zero-carbon technologies that still attract bipartisan political support. Although developing new systems is slow and expensive, nuclear reactors excel at providing 24/7 baseload power that can replace fossil fuel plants. 

Small modular reactors like the ones Kairos is building are particularly attractive for places that require steady amounts of power or lack reliable transmission infrastructure. They can operate around the clock in any weather conditions, and they are largely independent from the grid. 

Applications could include AI data centers, whose electricity consumption the International Energy Authority expects to more than double over the next five years, but also remote towns and safety-critical transportation hubs. Denver International Airport announced recently that it was exploring the possibility of constructing one such reactor, after over 1,000 flights at London’s Heathrow Airport were grounded or diverted earlier this year due to a substation failure.

Caveats

Although there have been numerous experimental molten salt reactors, no one has yet shown that they can operate one consistently and profitably over the long term. Building test reactors in parallel might shorten Kairos’s development cycle, but it could also reveal problems that cascade through the entire fleet. 

Furthermore, Russia’s invasion of Ukraine in 2022 slammed the doors on supplies of Russian uranium, including the fuel with a higher concentration of uranium-235 that’s needed to make the pellets for Kairos’s efficient reactors. The US and Europe have since been scrambling to mobilize domestic production, but the process will take years. In the meantime, the DOE has agreed to supply Kairos and a few other US companies developing similar reactors with limited quantities of the specialized uranium for their near-term fuel needs. 

Even with a regular supply, transporting that uranium to reactors won’t be straightforward. There isn’t yet a special container approved by the US Nuclear Regulatory Commission that could move it in any significant volume, and using existing containers could take thousands of shipments to fuel a single reactor. Kairos has said that it could potentially use a less enriched type of uranium to prove its technology’s viability while the supply of its desired version is tight. 

Next steps

Kairos is now building three reactors simultaneously —two non-nuclear test units to validate its systems, and the Hermes experimental nuclear reactor. These facilities will prove the molten salt technology at full scale, without generating any usable power. Kairos will soon start work on another, Hermes 2, which will be the company’s first system to produce electricity. 

When that 50-megawatt reactor comes online in 2030, Kairos will sell its power to the Tennessee Valley Authority, the US’s largest public power provider, and the associated clean energy credits to Google. Google has agreed to purchase up to 500 megawatts of generation capacity from Kairos by 2035 to help decarbonize its data centers. But take all those dates with a pinch of molten salt—nuclear power stations usually come in late and over budget.