1. A self-propelled deep-sea diving submersible, consisting of a crew cabin similar to a bathysphere suspended below a float: A bathyscaphe is a navigable, submersible vessel for exploring the depths of the ocean, having a separate, overhead chamber filled with gasoline for buoyancy and iron or steel weights for ballast.

The original bathyscaphe, constructed in 1948, was made of a cylindrical metal float and a suspended steel ball that could hold two people.

Design improvements allowed the second bathyscaphe in 1960 to descend to a record 10,912 meters (35,791 feet) in the Marianas Trench in the western Pacific Ocean, almost to the deepest level ever sounded on earth.

2. A "diving apparatus for reaching great depths", 1947, name coined by its inventor, Swiss "scientific extremist" Professor Auguste Piccard, from Greek bathys, "deep" + skaphe, "boat".