Bathyscaphe Trieste
On 23 January 1960, she reached the ocean floor in the Challenger Deep (the deepest southern part of the Mariana Trench), carrying Jacques Piccard and 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 , although this was revised later to ; fairly recently, more accurate measurements have found Challenger Deep to be between and deep.
USS Nero (AC-17)
"Nero" recommissioned on 10 April and sailed five days later for the Hawaiian Islands for deep sea soundings, then steamed via Guam to the Philippines arriving Cavite on 4 August. There she coaled various naval vessels until sailing on 9 September for Yokohama to continue deep sea sounding. The collier got under way for the west coast on 24 September, stopping at Guam and Honolulu and arriving Mare Island on 15 February 1900. During this voyage she took a sounding in the area of the Challenger Deep, recording a depth of 5269 fathoms (9,636 m, 31,614 ft), the greatest depth recorded at that time. She decommissioned on 20 May.