The Poseidon Project

The Poseidon Project is a 2013 documentary film about the search for a lost British submarine called HMS Poseidon. The submarine sank after a collision off the coast of China in 1931. It was widely assumed to be still present in the Bohai Sea,miles off the city of Weihai in Chinas Shandong Province until American author and scuba diver Steven Schwankert discovered that it had been salvaged by a Chinese salvage team in 1972. Schwankerts work and the history of the submarine and its crew is the subject of The Poseidon Project. The film was directed by British brothers Arthur Jones and Luther Jones.

HMS Poseidon collided with a cargo ship off the coast of China on June 9, 1931. Thirtyone of the submarines crew managed to scramble into the water before the submarine sank to the seabed 130ftm below. Butwere trapped inside. The submarine hit the headlines within hours because five men managed to escape from the submarine using the new Davis Submerged Escape Apparatus. They were the first people to escape from a downed submarine using protoscuba devices.The film charts Schwankerts efforts to examine the escape and the accident in unprecedented depth. It also follows him as he uncovers the secret salvaging of the submarine in 1972 by one of Chinas new salvage teams. The story is also told in Schwankerts book Poseidon Chinas Secret Salvage of Britains Lost Submarine. ........

Source: Wikipedia