This is called a "seabreacher". They're designed like dolphins or sharks, and they can travel under the surface as well as above like a regular boat. The movements they're capable of are a lot like that of a dolphin, see a video here.
See a video of seabreachers here... They're being custom built now, but I don't imagine it'll be long before they're being mass-produced. I read a starting price is around $65,000 for a basic model. I'll probably be needing one for my place here in Florida, another for my winter home in Hawaii, and another for my vacation villa in The Maldives. :D
