Underwater Exploration

The tool that made true exploration of the deepest waters of the seas possible is the deep-sea submersible vessel or vehicle, simply called a submersible. The submersible is a miniature submarine, but submarines are not submersibles. Submarines are fully contained quarters for human occupancy and for machines, usually with a military purpose, that can survive at depth for an extended length of time. Some nuclear-powered submarines stay submerged for months, carry food and fresh water for crews of over 100 persons, purify air for breathing, and perform specific tasks related to warfare, espionage, and research. While they also have highly sophisticated equipment, including sounding devices, pressure and temperature meters, and elaborate navigation and power systems, these are used for different purposes than the instruments on a research ship or submersible.

Submersibles are designed to dive to much greater depths than submarines. Because of the tremendous pressures in the deep ocean realms, they are built for strength, survival of two or three human occupants (if any), and specific research tasks. They do not carry stores of food or water, and oxygen is furnished from limited on board storage tanks or piped in from the support vessel at the surface.

Early submersibles were called bathyscaphs from the Greek roots for deep and boat, bathyspheres meaning deep-diving spheres, or diving saucers. The bathysphere was a steel diving chamber suspended from a host ship at the surface on a steel cable and a separate telephone cable. The bathyscaph also had a steel diving sphere, but it was suspended beneath a football-shaped blimp that carried gasoline to keep the craft afloat until the crew wanted to make the bathyscaph descend. For descent, the gasoline was released and replaced with seawater. Diving saucers were a specialty of the French; Jacques Yves-Cousteau designed an early diving saucer called the Soucoupe (the French word for saucer) that was unique in using hydrojets to maneuver in the water. Later saucer-like vessels, the Deepstar 4000 and the Cyana, also made landmark explorations into the underwater world. The Cyana was used in 1974 in the pioneering exploration of the Mid-Atlantic Ridge and its deep rift valley.

A number of countries around the world operate submersibles through their oceanic research organizations. Manned submersibles have descended to over 20,000 ft (6,000 m) deep; one of these, the Argo, was used by Dr. Robert D. Ballard to locate the wreck of the H.M.S. Titanic in 1985. After the Titanic's location was discovered using a manned submersible, a smaller, unmanned robot submersible named Jason ventured into the wreck to photograph its interior. Most submersibles carry still cameras, television systems, and special lighting systems to provide light for photography. All of these are designed and built specifically for the deep-ocean environment and its severely limiting hardships. Many submersibles are also equipped with mechanical manipulators (arms and scoops) that can collect samples from the sea floor, biological specimens, and oddities such as debris from the Titanic.