It's probably not a good time to be the purveyor of personal luxury submarines right now, what with global financial markets crashing and burning lowering the number of rich people dramatically. But hey, that doesn't mean said submarines aren't pretty awesome.
This submarine concept allows you to hang out under the surface, checking out coral reefs and fish populations. When you get bored with that, you can surface and treat it like a yacht, hanging out on the deck and soaking in the rays. The whole thing is powered by hydrogen fuel cells, in theory, making it nice and eco-friendly. If made, it would be very, very expensive.