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.
Submersible
Among the most well-known and longest-in-operation submersibles is the deep-submergence research vessel DSV Alvin, which takes 3 people to depths of up to 4,500 metres (14,800 ft). Alvin is owned by the United States Navy and operated by WHOI, and as of 2011 had made over 4,400 dives.