Water, a sweater, and 70s track shorts. Uh, what is a damn good time? YOU ARE CORRECT SIR!
Pedaling isn't just for the land. There's a whole bunch of nuts out there making human powered boats. The really cool ones I think are the Hydrofoils. Looks like you can really get cooking on one too. Although most of those look to be solar powered.
This fella has on his whole cycling get up. The linked page is full of human powered boats or HPBs as I like to call 'em.