So, you've finally arrived. That "See Food" app took off like a rocket, and with many millions to burn, you've bought yourself a 230-foot superyacht with all the fixings and a 4,000-nautical-mile range. How very tawdry. Let's talk about real wealth. We're talking $2 billion, James-Bond-villain, private-luxury-submarine wealth.

Bloomberg has a deep dive on the burgeoning world of companies aiming to build these full-size, yacht-like submarines for people with underwater bases and steel-toothed assistants. The gilded tube concepts being bandied about are a world away from the cramped submersibles used by private exploration outfits around the world, ranging in size from a 64-footer that looks more like a private jet to a hulking 928-foot monster whose arrival in any territorial waters seems like it would be likely to set off some kind of military response. [Fun fact: That's twice as long as the U.S.S. Jimmy Carter, the U.S. Navy's cutting-edge Seawolf-class submarine—which is in turn about 100 feet longer than other American hunter-killer submarines. —Ed.]

If someone actually steps up and orders one, that is. Nobody's done so yet, so it's all vaporware for now.

And that's the sticky wicket: Even though there are multiple company is offering a full lineup of right-sized subs—plus additional luxury designs available from two other firms—there are currently no private U-boats skulking around the waters of the world. Every render you've seen is just that: a render. The whole private submarine industry seems to be one expensive test of the If you build it, they will come theory of business.

But it's possible the gamble will pay off. Bloomberg reports Ocean Submarine is currently building its first customer vessel, with delivery of the 64-foot Neyk L3 reportedly scheduled for 2018.

Even if the thought of owning a private sub seems far outside the real-life experience of normal people, the $23.8-million Neyk L3 is a surprisingly straightforward take. It takes its design cues from the Gulfstream G650s and Cessna Citations of the world (going so far as to apparently use renderings based on pictures of private jet interiors), transporting up to 20 passengers in stately, aircraft-like accommodations.

The L3 will reportedly be built to international submarine safety standards; Ocean Submarine says it will also be able to maintain a fixed position underwater and pull smoothly up onto any sandy beach. Buyers can also opt to add custom touches, like a pressure chamber for impromptu scuba diving sessions.