Deep-diving Manned Submersibles
Some submersibles have been able to dive to great depths. The Bathyscaphe Trieste was the first to reach the deepest part of the ocean, nearly 11 km (7 mi) below the surface, at the bottom of the Mariana Trench in 1960. China, with its Jiaolong project in 2002, was the fifth country to send a man 3,500 meters below sea level, following the US, France, Russia and Japan. China's State Oceanic Administration (SOA) said a Chinese manned deep-sea submersible reached a depth 5,115 meters. The Jialong submersible was designed to reach depths of up to 7,000 meters below sea level and is expected to have a 7,000-meter test dive in 2012.
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.
Read more about this topic: Submersible