In 2010 three groups announced plans to develop and send a manned submersible to the deepest place in the World Ocean, the almost seven-miles-down “Challenger Deep.” Located in the Marianas Trench about 300 miles from Guam, it was discovered in 1951 by the British research ship HMS Challenger.
On 23 January 1960 the U.S. Navy’s bathyscaph Trieste with two men on board made a nine-hour dive to this deepest spot. (See “Dr. Piccard and His Wonderful Electric Submarines,” p. 102, September 2011 Proceedings.) No manned vehicle has been back in the 51 years since. However, two unmanned submersibles have done it. The first was the Japanese remotely operated vehicle (ROV) Kaiko in 1995 (and again in 1998). The other submersible was the unmanned/untethered vehicle (AUV) Nereus. Designed, built and operated by the Woods Hole Oceanographic Institution, it went to the Challenger Deep in 2009, spending ten hours at the bottom.