Because of the tremendous pressure, the depth to which a diver can descend without special equipment
is severely limited. The deepest recorded dive by a skin diver is 127 meters (417 ft). The deepest recorded dive
by a scuba diver is not much farther, at 145 meters (475 ft).
Revolutionary new diving suits, such as the "jimsuit," enable divers to reach depths
up to about 600 meters (2,000 ft). Some suits feature thruster packs that can boost a diver to different locations
To explore even greater depths, deep-sea explorers must rely on specially constructed steel chambers
to protect them. In 1934, American oceanographer William Beebe and engineer Otis Barton were lowered to about 1,000
meters (3,280 ft) in a round steel chamber called a bathysphere, which was attached to a ship on the surface by
a long cable. During the dive, Beebe peered out of a porthole and reported his observations by telephone to a colleague,
Miss Hollister, who was on the surface.
In 1948, Swiss physicist Auguste Piccard began testing a much deeper-diving vessel he invented
called the bathyscaphe. (This word is derived from the Greek words bathos -"deep" and scaphos -"ship".)
On an unpiloted dive in the Cape Verde Islands, his invention, named FNRS 2, successfully withstood the pressure
on it at 1,402 meters (4,600 ft), but its float was severely damaged by heavy waves after the dive.
In the 1950s, Jacques Piccard joined his father in building new and improved bathyscaphes including
Trieste, which dived to 3,139 meters (10,300 ft) in field trials.
The U.S. Navy acquired Trieste in 1958 and equipped it with
a new cabin to enable it to reach deep ocean trenches. In 1960, Jacques Piccard and Navy Lieutenant Donald Walsh
descended in Trieste to the deepest known point on Earth - the
Challenger Deep in the Mariana Trench. The two men made the deepest dive in history: 10,915 meters (35,810 ft).
Today, scientists are making exciting discoveries about the ocean floor, thanks to deep-sea submersibles
such as Alvin. Operated by the Woods Hole Oceanographic Institution
in Massachusetts, this three-person submarine made its first dive in 1964. Since then, Alvin has made more than 3,000 dives to average depths of 1,829 meters (6,000 ft).
Alvin has conducted a wide variety of research missions, from discovering
giant tubeworms on the Pacific Ocean floor near the Galápagos Islands, to locating the wreck of HMS Titanic in the Atlantic Ocean.
Alvin has met some amazing life on its travels, but so far it has
not encountered one of the deep sea's most mysterious inhabitants - the elusive giant squid. However, Alvin once was attacked by a swordfish, which became trapped between two pieces
of the sub's fiberglass skin. The fish was brought back to the surface and cooked for dinner!