Phil Nuytten first decided he wanted to spend his life underwater when he was six years old. It was 1947. The Second World War had only recently ended. Nuytten’s dad had scored a job at Boeing, and the firm’s office in Vancouver Harbour was just a short walk away from the family home. Every now and then Nuytten would waltz down to the harbour unaccompanied, sneak out to the end of the docks, peer through the cracks and fall hopelessly in love with what he saw: fish, anemones, a teeming underworld. “I used to think: ‘Gosh, wouldn’t it be wonderful to go down there?’” he says. “To go down to that particular place?”

I used to think, ‘Gosh, wouldn’t it be wonderful to go down there, to that particular place?'

Nuytten and I are sitting in his office, a wood-clad two-storey workshop on an industrial section of the North Vancouver shoreline not far from where he grew up. He is in his 70s now, scrupulously groomed and graciously quick-witted, with an old-time mariner’s flair for storytelling. He is also believed to be one of the world’s leading deep-ocean explorers. During a six-decade career he has pioneered diving techniques that are now industry standard, designed underwater machinery that has become a staple of several navies, and recorded world-first dives.

He has studied oil fields, surveyed dams, toured submarine construction sites and explored sunken wrecks. His firm, Nuytco Research, boasts a client list that includes the BBC, Greenpeace and film director James Cameron – Nuytten provided ideas and apparatus for The Abyss and Titanic and the pair remain friends. Nuytten also develops equipment for Nasa and, because the seabed is in some ways analogous to the surface of Mars, trains astronauts. Nuytten never went to college. He is almost entirely self-taught, yet the impact he’s had on ocean exploration has been vast.

Deep thinker: Phil Nuytten, self-taught underwater genius at Nuytco Research, his firm in Vancouver. Photograph: Peter Holst/The Observer

Now Nuytten is about to embark on a project likely to become his showpiece: a vast underwater colony, decades in development, that will provide humanity with an escape hatch should things go to pot above ground. Work will begin on a prototype later this year. A larger colony will follow soon after. So long as everything goes to plan, hundreds and then thousands of people will begin to migrate to the sea floor, to play out their lives at the bottom of the ocean in much the same way they would have done above ground. Before long, many more will follow.

Whether or not everything will go to plan is difficult to judge. “It’s a harsh environment,” James McFarlane of International Submarine Engineering tells me. “You’ve got salt water, corrosion… And when you get into the water things start to get expensive fairly rapidly.” Still, Nuytten is determined. He has given his entire life to developing methods that allow humans to spend inhuman amounts of time underwater, often at unimaginable depths. Now he’s in the final throes of a mission to move us all down there – and once we’re there, he doesn’t think we’ll ever want to come back up. “I have this wonderful picture in my mind,” he says. “A little kid is sitting on his dad’s knee, just as I used to do, and he points to the ceiling of this habitat and says: ‘Dad, is it true people used to live up there?’”

The idea the human race might one day live at the bottom of the ocean is not new – underwater habitats have been popping up in shallow waters since the early 1960s. In 1962 a French duo, Albert Falco and Claude Wesly, spent a week inside a minuscule habitat designed in part by the French explorer Jacques Cousteau. It sat 33ft below the surface on the sea floor close to Marseille and looked like a watery space station. The following year Cousteau convinced a five-person team to live for a month beneath the Red Sea, off the coast of Sudan. Two years later he developed a third base, Conshelf III, which he anchored more than 300ft below the surface off the coast near Nice. A six-person team lived there for three weeks. Every day they left the base to work on a mock-up oil rig. It was hoped inhabitants would perform similar work in the future, by which point the rig would be real.

Before long, additional habitats materialised off the coasts of Bermuda, California and Germany. Bases were funded by governments, wealthy patrons or the petrochemical industry, and there was huge academic optimism. Here was an opportunity for scientists better to study the ocean’s inky depths, aquanauts to study human anatomy, energy companies to discover alternate resource streams and divers to launch record-breaking descents.

In the 60s everybody believed there would be cities under the sea

“In the 60s everybody in the ocean business firmly believed there would be cities under the sea in fairly short order,” Nuytten says. “Never happened.”

By the end of the decade the race to colonise the bottom of the ocean slowed to a trot, then all but petered out. The habitats were expensive to build and even more expensive to run. The lack of natural light could send tenants loopy. And, because the bases were built at ambient pressure, decompression periods were long and risky. Teams would spend weeks at a base, conduct tests, learn more about the limits of human endurance, slowly resurface to land and, in many cases, never return. One by one the habitats were abandoned. Research institutions diverted funds elsewhere. Government agencies shifted their attention skyward. Space replaced the Earth’s oceans as our final frontier.

At the time Nuytten was still a rookie in the ocean industry. He had begun to work on the concepts for which he would later be lauded, but Cousteau’s experiments, which to many seemed more like science fiction than reality, never strayed far from his mind. The subject became a kind of obsession. What if he could create a habitat that was cheaper to build and cheaper to run? What if he could find a way to reproduce the natural light man needs to exist comfortably? What if he could overcome problems caused by the deep ocean’s almighty pressure? And what if he could do what Cousteau and his contemporaries could not: convince society it would be a good idea to live 3,000ft under the sea?

Super subs: underseas vehicles at at Nuytco Research. Photograph: Peter Holst/The Observer

In his office, Nuytten tells me he works best when big questions like these loom overhead. “I run around looking for needs so I can fill them in. I like to have about 10 things on the go at once.” Nuytten is a perennial tinkerer, most effective when there are problems to solve, and the barriers to successful underwater living posed interesting problems.

By the end of the 60s he had begun work on his own colony, which he began to refer to as Vent Base Alpha. Every now and then he’d scribble ideas on paper scraps and file them away, gradually accumulating hypotheses. Whenever he developed a new piece of technology, usually for a client, he’d experiment with how it might be incorporated within plans for the base. Sometimes a sketch would lead to a breakthrough, and he’d be able to understand what went wrong the first time someone tried to live under-water. What followed was half a century of successes and setbacks. Now a working vision has emerged.

Here’s how Nuytten plans to build the colony. First, he’ll forage for equipment in what he calls “the boneyard”, a huge lot in which he stores discarded apparatus. (“I never throw anything away. I am a hoarder.”) He’ll locate a stack of abandoned saturation tanks and convert them into living quarters, laboratories, a series of floodable airlocks and a hangar for submersibles, each tank impeccably welded to the next. Later, he’ll equip the structure with a Stirling engine capable of producing the electricity required to create artificial sunlight, allow inhabitants to grow crops and, crucially, enable them to “crack water into hydrogen and oxygen”. Nuytten relays this last piece of information urgently. “There’s your life support,” he says.

The colony will be transported to open water, most likely the Juan de Fuca Strait, a 154km-long outlet to the Pacific Ocean south of Vancouver Island. It will be submerged and hauled to the sea bed a few thousand feet below, and then it will be installed next to a hydrothermal vent – a kind of underwater geyser. The vent will give the colony its name, its hot emissions will power the Sterling engine and its mineral-rich deposits will be mined. Inhabitants will trade the bounty – laboratory-pure cobalt, in the case of the Juan de Fuca Strait – with buyers above the surface. Nuytten will make no financial gain from the project. Funding will come from government agencies, though Nuytten will forgo requesting official permission over whether or not a huge heap of metal can be attached to the ocean floor, preferring instead to “beg for forgiveness” after the installation – his customary strategy. (The prototype, in contrast, will be sanctioned by an offshoot of Fisheries and Oceans Canada, a government body, and anchored in the Burrard Inlet, not far from Nuytten’s office.)

When the colony is complete, Nuytten will be among the first to take the plunge. His wife Mary, to whom he has been married for more than 60 years, will follow. As will his daughter, Virginia, if only for a visit. “I’m a mad-keen gardener,” she tells me over the phone. “If I couldn’t have my plants with me, I wouldn’t want to be there.” Soon enough, the family will be joined by other members of the ocean community: scientists, engineers, oceanographers, as well as James Cameron, who has already reserved a berth. Within a few weeks the base’s early tenants – a dozen or so people – will have settled into a routine.

At least in the beginning, inhabitants will live underwater for months at a time, though they will be able to come and go. The atmosphere within the colony will tally with that on the surface, eradicating the requirement for decompression and making travel between the two worlds “like taking an elevator down to the parking garage”, explains Nuytten. But, soon enough, we will live at 3,000ft below as though it were normal. The colony will expand. More and more people will slip below the surface to begin second lives, and new colonies will appear around the world. Our routines won’t change, just the environments in which we perform them. We will do the things we normally do: commute to work, gossip with friends, spend inordinate amounts of time on social media. There will be underwater hospitals, banks, galleries, offices, parks, gyms, cinemas, farms, maybe even a forest or two. Children will be born in the colony. Eventually they will die there, too.

But all of that will come down the line. First, Nuytten says: “We’ll have to figure out what we want to do down there.” He stops, then adds: “None of this has been done.”

Marine boy: Phil Nuytten at Nuytco Research. Photograph: Peter Holst/The Observer

During our conversation Nuytten shows me an artist’s impression of the base. It’s an image of a structure that looks much like an underwater power station – a great mass of welded metal, similar to that of a rig. To the right of the picture a hydrothermal vent spouts sooty emissions and divers mine the ocean floor for minerals. Inside, inhabitants resembling Star Trek characters tend to operations. The surrounding environment looks dark and eery, a permanent night. You’d have a hard time working out what time of day the image depicts.

I ask Nuytten why we would ever need to live underwater. “We need a second place to go,” he says. “There’s less and less space on Earth, and fewer and fewer resources. And here’s a whole ocean filled with them.” Nuytten is a fierce conservationist. “The oceans are the lungs of this planet. If they go, the planet goes.” In his grand vision, the colony is a kind of salvage operation. It will enable humanity to alleviate the burden it has placed on land. “We’ve demonstrated there will come a time when the planet as we know it will not be able to support the population. The population keeps growing and growing, and with climate change and natural disasters on land getting to be excessive… As far as we know, those same things aren’t happening under the sea. That’s one of the things we want to study: what are the effects of climate change on the deep ocean? We know what the effect is on the shallow regions, the coral reefs, but what about 3,000ft down? What’s happening there?”

But how easy will it be to convince other people to take the plunge? “They’d batter the doors down,” he said. “Literally. I’ve given a lot of talks on this, and I’ve had all kinds of people, from wackos to really serious people, saying: ‘If you do this, we want to go.’”

All sorts of people have said, ‘If you do this, we want to go’

This seems like a hopeful response. Nuytten has spent much of his life below the surface. To him, the ocean is home. But what about the rest of us? What about the isolation? What about not being able to go anywhere any time we wanted? Won’t we miss the sun?

Nuytten tells the story of an advertisement he’d heard had once been placed in a local UK newspaper. It read, “Wanted: people to go to Antarctica. Poor pay. No guarantee of success. Doing things no one has done before.” “They were inundated with applications,” Nuytten recalls. “I expect that to be the case with this. There are so many people, particularly young people, who are desperately trying to figure out what to do, what they can do that nobody else has done, things that are difficult, things that will protect our oceans.” The first inhabitants will be pioneers, Nuytten believes. “Once you have the first group down there, staying a few months, the next batch will show up.”

Nuytten is in no doubt the colony will succeed. “There were an awful lot of people who said we’d never fly in the air,” he tells me. “And even more who said we’d never go to the moon.” But his comment is underpinned by a more urgent message, one that moved the conversation away from personal success and into the realms of societal requirement. “What are we going to do if something catastrophic happens to where we live?” he says, resignedly. “We have to have some place to go.”