Make:

The latest New Scientist has a piece on Ted Ciamillo, the machinist who invented the hydrospeeder (think: Bondian underwater motorcycle) and the Lunocet (a tail for divers modeled on dolphins). Ciamillo's latest project is a human-powered mini-sub he plans to use to pedal across the Atlantic:

Ciamillo designed his mini-submarine around a larger version of the Lunocet. The body of the vessel is built from lightweight yet tough materials: a stainless steel frame, a polycarbonate shell and a propulsion system made from aluminium and titanium. It will operate as a "wet" sub: instead of having a pressurised shell filled with air, it will be full of water at all times. Buoyancy is provided by PVC foam packed into the shell and from air bladders that can be filled or emptied to keep the vessel at the desired depth. At 1.2 metres at its widest point by 5 metres long it is not exactly roomy, but neither is it claustrophobic. "Being weightless, with all the windows, you feel like you have plenty of room," Ciamillo says.

Across the ocean in a pedal-powered submarine

More:

• American Maker: The Winner "Airheads Air Drums"
• Build your own one-person submarine