Fathoms beneath the ocean’s waves, luxury submarines beyond even Ian Fleming’s imagination are roaming a deep seascape like the most preposterous Pinewood studio set brought to life. The masters of this marine universe are the most secretive of people, whose wealth enables them to slip beneath the radar of the FBI and the CIA.

Privacy and paranoia ensure that nobody knows for certain who is down there. Today’s new super-submarine club is as exclusive as it gets: the commanders of global wealth can count themselves, and their extravagant new toys, on their fingers, unlike their multi-billion- pound business dealings.

Paying up to £50m for the privilege of vanishing off the face of the earth for weeks at a time, the world’s richest men have entered into an unseen competition for status. For in the spirit of Jules Verne’s idealistic Captain Nemo in 20,000 Leagues Under the Sea, they have made the vast ocean deeps their own personal playground. “When you get over to the Riviera and you roll that sucker out of the stern of your yacht, it’s saying: I’ve got something you haven’t!” says Don Walsh, a veteran ex-US Navy submarine captain. He has seen it all during his 50-year career beneath the seven seas — including taking a sub the deepest ever recorded, to 35,760ft in the Pacific Ocean’s Mariana Trench. It’s a record that’s unlikely to be threatened, no matter how much money the rich throw at the designers of their underwater craft.

Even the worldly-wise Walsh is left breathless by today’s unprecedented display of seafaring one-upmanship. He says the super-submarine race was launched by Paul Allen, co-founder of Microsoft, who shelled out £6m for the 40ft yellow submarine that sleeps eight and docks in the aft of his mega-yacht, Octopus.

The race has become a game of keeping up with the Abramoviches. The Russian oligarch-turned-Premier League football club owner Roman Abramovich is reported to have his second submarine on order, apparently from the leading manufacturer US Submarines. Its 65ft Nomad 1000 costs a cool £3m and has a luxurious interior similar to an executive aircraft. It will dock — James Bond fashion — in a subaquatic chamber built into his new 550ft super-yacht, Eclipse. It is, nevertheless, only a plaything.

Reports claim that Abramovich’s first commission from US Submarines was the Nomad’s bigger sister, the Seattle 1000. Costing £13m to buy and £1m a year to run, the 118ft Seattle feels like an undersea luxury yacht, boasts two deck levels, staterooms, dining rooms, separate guest and crew living areas, and sufficient cruising range for transatlantic crossings. Oh, and the option of 1,000ft, deep-sea exploration and two weeks’ submerged cruising. The billionaire is said to have boasted, “If you can find my submarine, it’s yours.”

While submersibles of all sizes have moved on from previously utilitarian roles as unseen predators and vehicles for scientific research, Walsh admits that, regardless of their positioning as status symbols, the thrill of deep-sea adventure is unrivalled.

“Most marine life can be found in the upper 100ft of the ocean. In plankton-rich areas you’re losing the light at 400ft, passing through shades of grey, and at 1,000ft you have complete extinction of light. A dive capability of 1,000ft is a good trade-off: the continental shelf is roughly 600ft at the outer edge, and once you leave that you’re into a whole deeper, darker ocean. You’re nibbling at the edge of the abyss.”

Fulfilling rich men’s dreams is the ambition of pioneers such as Bruce Jones, chief executive of US Submarines. His lips are sealed, however, when it comes to clients or orders. “I’d say the majority of our customers buy our submarines for the excitement of exploration and the sense of there being a great unknown. I’m not going to tell you who they are. Last time I mentioned a name, I ended up being sued. These are people who value their privacy.”

US Subs’ masterpiece is currently awaiting a buyer. The Phoenix 1000 looks like a luxury yacht with very large acrylic viewports, but beneath its streamlined 213ft exostructure sits a state-of-the-art, high-tensile steel pressure hull, capable of withstanding dives to 1,000ft and staying submerged for three weeks. The cruel irony facing Jones is that his wildly luxurious designs restrict potential buyers to the world’s richest people, so orders for multi-million-pound vessels don’t exactly come flooding in. “Unfortunately, there aren’t too many mavericks prepared to take that first leap of faith while others watch.”

The super-submarine’s plans sit on Jones’s computer, waiting for the Phoenix to rise. Or rather, dive. “I’m confident we can find a buyer. How do I know that? Well, consider this: there are currently in construction 775 yachts longer than 100ft. Each one of those costs a minimum of £7.5m. There are more than a hundred 400ft super-yachts in construction, which cost about £200m each. At £50m, the Phoenix 1000 represents fantastic value.”

Capable of transatlantic crossings at sea level, with a speed of 16 knots and range of 3,500 miles, the imperious Phoenix 1000 would rival super-yachts for cruising potential, but the novelty would lie in leaving a storm raging above you by diving to serenity.