Trieste.

On 23 January 1960 the bathyscaphe Trieste, a manned vehicle designed to dive into deep seas, dove to about 37,000 feet in the Mariana Trench of the Pacific Ocean. Inside were twenty-eight-year-old navy lieutenant Don Walsh and thirty-seven-year-old Frenchman Jacques Piccard. Piccard's father designed and built the Trieste in Italy for the U.S. Navy. The dive took four hours and forty-eight minutes; the Trieste spent half an hour at the bottom, where the hull withstood pressures of over 17,000 pounds per square inch.

Rough Descent.

Trieste dove 4 feet per second to 27,000 feet. The first part of the dive was smooth compared to the rough seas above. Then Trieste hit a thermo-cline, where water temperatures drop sharply at a certain depth, causing the relative weight of the craft to increase. There were thermoclines at 250 feet and again about 400 feet. The second was thick and caused the craft...