These are in the design stage so far. No buyers yet.

For those bored with multimillion-dollar megayachts, with their ho-hum helipads and snooze-inducing jacuzzis, consider the 928-foot-long M7, designed by the Austrian company, Migaloo Private Submersible Yachts.

If you’re the helipad-on-a-sea-vessel type, the M7 not only has a place for your chopper to land, it has a swimming pool, VIP suites, multiple hangar bays, and a design inspired by the U.S. Navy’s Zumwalt-class destroyers. (Alas, its engines are diesel-electric, not nuclear-powered.)

And unlike a yacht, which is just going to sit there on top of the water, floating around like a $200 million chunk of burnished driftwood, the M7 can dive to 1,500 feet and cruise underwater at 20 knots. The real excitement, as Sebastian the Crab once sang, is “under the sea.”

Life may be better down where it’s wetter, but the M7 will cost you. There’s no precise price tag yet, says Christian Gumpold, chief executive officer of Migaloo. But the $2.3 billion figure mentioned in this report is close. “This would make it for sure to the most expensive private object worldwide,” Gumpold told us via email.