USS Seawolf SS-197 completed 14 successful patrols hunting Japanese vessels through the Southeast Asian waters before inexplicably vanishing in October of 1943.The submarine had been built just in time for World War II and was launched in 1939 before heading to the Pacific.During her impeccable career, Seawolf sank 27 ships and damaged 13 others, ranking 14th in the list of most prosperous US submarines that served in the war.However, after a Japanese submarine attack on her 15th patrol, the U-boat suddenly disappeared, creating confusion amongst the US forces and immediately becoming a source of wide speculation.