A design conceived by Francois-Alexandre Bertrand and naval architect Philippe Roulin, the Platypus Submarine is an innovative boat-submarine hybrid that can travel both above water and under water.
The Platypus Submarine has a central hull, where riders are meant to sit, flanked by two pontoons, which are joined by four horizontal arms. When these arms are horizontal, the craft acts like a jet ski and the riders can travel on the water's surface. The same four horizontal arms can also rotate downward; when this happens, the center section dips into the water and takes the riders under water.
As Diseno-Art points out, however, the two outer pontoons stay at water level at all times, meaning the Platypus Submarine isn't a real submarine -- not in the actual sense of the word. Even if it can't ever submerge completely under water, the Platypus is still a cool design by anyone's standards.