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  n January 23, 1960, the Trieste reached the bottom of the Challenger Deep in the Pacific Ocean's Marianas Trench and set a deep-diving record -- 35,810 feet -- that will likely never be bested. No one has even tried. In fact, in the nearly 40 years since, no person has plunged to within 10,000 feet of the record.

The Trieste, designed by Swiss scientist Auguste Piccard, was a bathyscaphe, or "deep boat." Before bathyscaphes, the deepest-diving vessels were bathyspheres -- steel spheres lowered and raised by a cable attached to a mother ship overhead. The Trieste and the bathyscaphes that preceeded it, on the other hand, could descend and ascend on their own.

Jacques Piccard and Don Walsh
Nearly four decades after their historic journey, Jacques Piccard and Don Walsh recount their experience on the Trieste.
The Trieste was over 50 feet long, and its deck, rails, and conning tower made it look something like a submarine. Most of it, however, consisted of floats filled with gasoline -- 70 tons of it. Gasoline is lighter than water, and so provided buoyancy; air tanks at either end of the ship allowed it to float on the surface before the beginning of the dive. Divers Jacques Piccard (Auguste's son) and Navy Lieutenant Don Walsh were confined to a six-foot-diameter, 14-ton spherical steel capsule at the base of the ship.

Piccard and Walsh began their descent by flooding the air tanks with sea water. Some nine tons of steel pellet shot helped them to sink. The gasoline compressed as the depth increased, and the craft became less buoyant -- speeding its descent even more (valves released some of that fuel to slow the ship down). Less than five hours after they left the surface, Piccard and Walsh touched down onto the floor of the very deepest part of the ocean -- where the crushing pressure exceeds 16,000 pounds per square inch (more than a thousand times greater than the pressure at sea level), and where Piccard reported seeing a fish swimming by. The divers then released the steel shot, and began their rise to the surface.

The Trieste was later used to locate the sunken nuclear submarine U.S.S. Thresher, and collected photos and other data from another sunken submarine, U.S.S. Scorpion, but it would never again touch the bottom of the sea. The original Trieste is now on display at the Navy Museum in Washington, DC.

-- By Kathy Svitil

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