Bathyscaphe Trieste - The Mariana Trench Dives

The Mariana Trench Dives

Trieste departed San Diego on 5 October 1959 for Guam aboard the freighter Santa Maria to participate in Project Nekton, a series of very deep dives in the Mariana Trench. On 23 January 1960, Trieste reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard (son of Auguste) and U.S. Navy Lieutenant Don Walsh. This was the first time a vessel, manned or unmanned, had reached the deepest known point of the Earth's oceans. The onboard systems indicated a depth of 11,521 metres (37,799 ft), although this was revised later to 10,916 metres (35,814 ft); more accurate recent measurements have found the Challenger Deep to be between 10,911 metres (35,797 ft) and 10,994 metres (36,070 ft) deep.

The descent to the ocean floor took 4 hours and 48 minutes at a descent rate of 0.9 metres per second (3.0 ft/s). After passing 9,000 meters one of the outer Plexiglas window panes cracked, shaking the entire vessel. The two men spent barely twenty minutes at the ocean floor, eating chocolate bars for sustenance. The temperature in the cabin was 7°C (45°F) at the time. While on the bottom at maximum depth, Piccard and Walsh unexpectedly regained the ability to communicate with the surface ship, USS Wandank (ATA-204), using a sonar/hydrophone voice communications system. At a speed of almost a mile per second (about five times the speed of sound in air), it took about seven seconds for a voice message to travel from the craft to the surface ship and another seven seconds for answers to return.

While on the bottom, Piccard and Walsh observed a number of small sole and flounder. Their claim that the fish were swimming would prove that at least some vertebrate life can withstand the extreme pressure at the oceans' deepest point. They noted that the floor of the Challenger Deep consisted of "diatomaceous ooze". The ascent to surface took 3 hours, 15 minutes.

No manned craft returned to the Challenger Deep until 26 March 2012, when the dive was accomplished solo by the film director James Cameron in submersible Deepsea Challenger. Three other teams are preparing for attempts in 2012. A Japanese robotic craft Kaikō reached the bottom of the Challenger Deep in 1995. The Nereus hybrid remotely operated vehicle (HROV) reached the bottom on 31 May 2009.