Last Known Activity Was a crewmember of USS THRESHER (SSN-593)
Most likely cause of the sinking was a failure in either a pipe, a pipe valve, or a hull weld, causing flooding near the engine room
The second USS Thresher (SSN-593) was the lead boat ofher class of nuclear-powered attack submarines in the United States Navy. Her loss at sea in the North Atlantic during deep-diving tests approximately 220 miles east of Boston, Massachusetts, on 10 April 1963 was a watershed event for the U.S. Navy, leading to the implementation of a rigorous submarine safety program known as SUBSAFE. Measured by lives lost, historic context and significance, the sinking of Thresher was then, and remains today, the world's worst submarine disaster. As the first nuclear submarine lost at sea, its disappearance generated international shock and sympathy.