The bathyscaphe Trieste as it appeared just before the record dive to the floor of the Marianas Trench. *

Image: Courtesy of the U.S. Navy * 1960: The diving submersible Trieste descends to the floor of the Mariana Trench, the deepest known place on earth.

The Trieste, a bathyscaph, was designed by a Swiss scientist and built in Naples, Italy, as a deep-diving research vessel. After proving its mettle in the Mediterranean, the Trieste was purchased by the U.S. Navy and shipped to San Diego.

Its dive into the Challenger Deep, the deepest part of the trench, was made, according to a Navy press release, "to demonstrate that the United States possesses the capability for manned exploration of the sea down to the deepest part of its floor."

The vessel was equipped with air tanks that could be flooded, like a submarine, to help it dive. Additionally, it was weighted down with nine tons of iron shot. Trieste descended at a rate of three feet per second to a depth of 27,000 feet, when its descent rate was halved.

It took Navy Lt. Donald Walsh and Jacques Piccard, the son of Trieste's designer, four hours and 48 minutes to make the descent to a depth of 35,810 feet, roughly seven miles. At seven miles down, the pressure is nearly 17,000 pounds per square inch. Although an outer Plexiglas window cracked during the descent, Trieste handled the dive like a champ.

After sitting on the bottom for 20 minutes, eating candy bars and shining a light outside that illuminated a shrimp-like creature, Walsh and Piccard pumped out two tons of iron shot and began their ascent. The trip home was faster – three hours and 17 minutes to the surface.

In 1963, Trieste was sent to the Atlantic Ocean to search for the nuclear attack submarine USS Thresher, which was lost with all hands during a deep-diving exercise. Upon its return, the bathyscaph was retired to the Navy Museum in Washington, D.C.

(Source: University of Delaware)

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