An Underwater Sports Car, by Way of the Netherlands

It was a customer's idea: his current submersible was fine, but it wasn't able to keep pace with certain marine life, the likes of sharks or sea turtles. Could U-Boat Worx, one of just a few makers of submersibles for the commercial market, build him something akin to an underwater sportscar?

"The result is actually more like flying underwater and something very different to what's available on the market at the moment," says Roy Heijdra, Head of Marketing of Netherlands-based U-Boat Worx, of its new Super Sub, capable of diving to 300m with an underwater speed of 10 knots, that's 4 knots faster than a bottlenose dolphin. One vessel has so far been delivered, with two in the pipeline. "Speed also opens up new avenues for marine research," he says.

Certainly, while many submersibles are bought for professional use (in science, or for the communications or oil and gas industries, for example) the commissioning of ever bigger private yachts capable of carrying a 7m, 9000kg diving vessel is seeing a rise in private owners. Larry Connor, James Cameron and Jeff Bezos are just a few of the more famous super-wealthy individuals prepped to explore the depths.

Advances in tech, from stronger, thicker acrylics to more compact electronics, easier launch systems to longer dive times, are making submersibles more user-friendly too, opening up a market that 20 or so years ago didn't exist. To date there are only around 200 private, non-military submersibles in operation around the world, according to Kohnen, compared with over 24,000 private jets (according to private jet marketplace Jettly).

"For submersible owners it's the next best thing to going into space," suggests Charles Kohnen, co-founder and chairman of California-based submersibles manufacturer SEAmagine. It recently opened a submersibles pilot training school in California, one drawing potential owners who want a better understanding before they commit between US$5 and $7 million.

"There are two types of customer," Kohnen explains. "There are those who want to explore wrecks, and for these the fish get in the way of their view, and those who see wrecks as a kind of littering and want to go deep enough to see in real life the kind of sea-life they've only ever seen in pictures. Or maybe never. We actually know very little about what's below just 100m depth."

Owners also want to be able to share the experience, to talk with their companions about what they see as they see it, so while one trend in submersibles is for speed, the other is for size. SEAmagine's newest vessel, for example, is the Aurora-100, a seven-seater, capable of some 3 knots underwater, but 450m depth, says Kohnen. These new options are also helping this fledgling industry counter the blowback caused by the implosion of OceanGate's Titan submersible three years ago, killing all five people on board.

"The media has done a good job of explaining how the accident was a one-off, and how that vessel was entirely unregulated [its design drew widespread scepticism, it was not independently 'classified' and operated entirely in international waters to avoid governmental jurisdiction]," says Heijdra. "But naturally it's been a challenge for what is still a small, niche industry. We have to talk about safety all the time."

Indeed, to reassure, 'classified' (which is to say safety certified) submersibles have full redundancy for all systems, days' worth of emergency oxygen and vessel-to-surface communications systems. They're also rated for depths many times their stated specification and are built with positive buoyancy: left alone they just float to the surface. "The safety of the submersibles is one reason why they're so expensive," Heijdra notes.

For the time being at least. With science and industry seeing increased acceptance that not all underwater work can be done by robotic ROVs, and with sales driving down the cost of tooling, submersibles are expected to get more affordable. You may still need a sizable super-yacht to put yours on though.