Not exactly the most common boat you will see at your local boat launch. The SCUBACRAFT Personal Submarine will be available in 2010. There is an interview over at James List that you may be interested in if you have some extra cash burning a hole in your pocket.

"The modular configuration allows for the electric system to be removed and replaced as necessary, adding extra batteries for extended operations or more thrusters for more power. A wide range of accessories including lights and cameras can be added to extend its underwater capability and enhance the user’s experience. Scubacraft uses a high powered jet propulsion system that will easily tow a water-skier and inflatable water toys. The trimaran hull configuration gives inherent stability as a diving platform and with its air entrapment design, results in high speeds on a cushion of air."