SO MY POST ON CIVILIAN SUBMARINES THE OTHER DAY led me to the U.S. Submarines website, where I learned of some pretty impressive private subs:

The Phoenix 1000

The ultimate personal transportation device, 65 meters (213 ft.) in length with 470 square meters (5000 sq. ft.) of interior space on 4 levels.

Powered on the surface by twin turbocharged marine diesels, all of our luxury submarine models, with the exception of the small Triton 650, have extended surface range and are capable of diving to 305 meters (1000′). Bad weather? Simply close the hatch and dive, cruising effortlessly far below the waves in air conditioned comfort. The submarines’ battery capacity and life support systems allow you to stay submerged for days at a time.

That’s pretty cool, though some of this stuff seems to be projected rather than currently available.