On April 10, 1963, the nuclear submarine Thresher was lost when it was doing scheduled depth tests off the continental shelf in the Atlantic Ocean. The disaster and the reasons behind it have been shrouded in secrecy. This secrecy was the order of the day during the Cold War, but still exists, especially when it talking about the submarine fleet.
And here is the Ballad of the Thresher by the Kingston Trio:
Gunsmoke and Knitting 