For the billionaire bored with superyachts, help is at hand: an Austrian company is promoting luxury vessels that double up as submarines.

The Migaloo M5, a “submersible superyacht”, would be 165m long, capable of diving to a depth of 250m and staying submerged for four weeks. It would comfortably accommodate up to 20 passengers, plus a crew of up to 40.

There would be room for jet skis, two six-person mini-submarines and a helicopter, and it would boast a 36-seat dining room with glass walls affording views of marine life.

The ideal gift for a Bond villain would cost about $2 billion to build — the exact price depends on optional extras such as a swimming pool, wine cellar or cinema.

Christian Gumpold, chief executive at the Graz-based design firm Migaloo, has been touting the idea of luxury submersibles for the past decade, without takers so far.

The firm has even designed a private floating island, the Kokomo Ailand, complete with living palm trees, waterfalls, private harbor, beach clubs, underwater dining station and a shark-feeding station.

It has come up with enticing computer renditions of these innovations and regularly updates them on social media. One recent Facebook post advertised the Limo Sub Tender, a submersible that allows people to access their submerged supersub “unseen and undetected.”

James Bond with the villainous Karl Stromberg inside his submarine, Atlantis, in The Spy Who Loved Me, 1977.

Gumpold told The Times: “We are currently in negotiations with a number of interested parties from all over the world who are motivated to own the world’s first superyacht-submarine hybrid.” He declined to name them.

“Our target group are visionary billionaires with or without existing superyacht experience who have extraordinary demands for exclusivity, safety, adventure or experiences and find our 165M private submarine concept appealing for these reasons,” he added. “As it is a completely new development, such a project will require corresponding monetary resources, take a lot of time for design, construction and building and demand many decisions.

“However, the owner also receives the corresponding prestige and unimagined new possibilities when calling this product his own. Our target group must be aware of this and have the corresponding innovative mindset.”

Migaloo has been touting the idea of luxury submersibles for the past decade, without takers so far.

He recommended that the vessels be built by experienced shipyards in Germany, Italy or the Netherlands, as was usual in the superyacht sector for vessels larger than 100 meters.

Gumpold regards luxury submersibles as the “future of yachting”. Owners are getting younger and yearning for more extraordinary and individual designs than “normal” surface yachts, he has said. Given market trends, he may be onto something.

According to researchers at Berenberg, Russia’s invasion of Ukraine has hit demand for conventional superyachts because the industry has been tainted by its association with Russian oligarchs. An estimated 15 yachts belonging to wealthy Russians have been impounded under Western sanctions since the war broke out.

The percentage of ultra-wealthy people with yachts has been falling for years, peaking in 2014 at 3.6 percent and declining to 2 percent in 2021.

Meanwhile, the global number of wealthy people who can afford yachts is growing.

Industry experts have voiced doubts about submersibles’ commercial viability given the level of engineering involved. There could be legal hurdles too, with countries unlikely to allow large submarines to comb coastal waters filled with antique treasures and natural resources.

“Our target group are visionary billionaires.”

Then there is the safety aspect, especially since public faith in underwater technology was dented by the implosion of the small submersible Titan during an expedition to view the wreck of the Titanic in June.

Migaloo is confident on that score, promising maximum safety with a double-hull construction and a range of rescue systems including mini-submarines.

It says it could put buyers in touch with shipbuilders in Germany, home to the makers of some of the world’s biggest superyachts including Lürssen. Lürssen says it has built 12 of the 20 longest yachts in the world, including the longest one, the 180m Azzam, reportedly built for Sheikh Khalifa bin Zayed Al Nahyan of Abu Dhabi’s royal family.

David Crossland is a Berlin-based journalist