bathyscaphe

Any free-moving vessel designed for underwater exploration, consisting of a flotation compartment with an observation capsule underneath. Originally designed by Auguste Piccard in 1948, they have proved capable of reaching depths of over 10 000 m/32 000 ft. Modern submersibles (such as Alvin, which explored the Titanic) are much more manoeuvrable.

A bathyscape, bathyscaphe, or bathyscaph is a free-diving self-propelled deep-sea diving submersible, consisting of a crew cabin similar to a bathysphere suspended below a float (rather than from a surface cable, as in the classic bathysphere design).

To descend, a bathyscaphe floods air tanks, but unlike a submarine the water in the flooded tanks cannot be displaced with compressed air to ascend, because water pressures are typically too great. Instead, ballast in the form of iron shot is released to ascend, the shot being lost to the ocean floor. The iron shot containers are in the form of one or more hoppers which are open at the bottom throughout the dive, the iron shot being held in place by an electromagnet at the neck.

Auguste Piccard, inventor of the first bathyscaphe, composed the name bathyscaphe using the Greek words "bathos" (depth) and "skaphos" (ship).

Piccard's second bathyscaphe was Trieste, which was purchased by the U.S. Navy in 1957. It had two water tanks and held 120,000 litres of petrol in eleven tanks for buoyancy . In 1960 Trieste, carrying Piccard's son and a U.S. Naval officer, set a world record by diving to a depth of 35,810 feet (10 915 metres) at the bottom of the Challenger Deep, the deepest point in the Mariana Trench and believed to be the deepest point in the world's oceans.