A nifty powerboat/submersible that can handle water and when under power dive. Positive flotation will bring it back to the surface if power dies.

The Hyper-Sub is the first small craft built with the horsepower, sea-keeping, and range to allow operation on the high seas, which also functions as a self-charging, autonomous, one-atmosphere submarine.

Mad Mariner™ had a nice slideshow last week on this vessel with lots of pictures.

For full disclosure, I write some paid articles for Mad Mariner™.