Forty-six years ago today on April 10, 1963, the nuclear submarine U.S.S. Thresher, while conducting dive tests, sank around 200 miles east of Cape Cod, Massachusetts. It imploded at crush depth, killing all 129 officers, crew and civilian contractors on board.
For submarine nerds — yes, there are some of us — the sinking of the Thresher provides fascinating and somewhat ghoulish reading on naval procedures and nuclear reactors. The board of inquiry into the Thresher disaster concluded that salt water pipes on the vessel probably leaked, leading to a shorting-out of control panels and an automatic “scram” (emergency shutdown) of the nuclear reactor; once the reactor had been shut down, the steam tubes providing power to the turbines were vacated and the reactor could not be quickly restarted. The Thresher was already almost at its maximum depth, so it didn’t have far to go before the vessel imploded, killing everyone on board in a second or two. The sinking of the Thresher led the U.S. Navy to completely revise its submarine safety procedures, following much criticism of sub fleet commander Hyman G. Rickover.
Interestingly, one of the vessels searching for the Thresher after it sank was the famous bathyscaphe Trieste, which broke the deep-sea diving record in the Marianas Trench in the Pacific.
The Wikipedia article on the Thresher, from which some of this info is taken, has a fascinating GIF animating the events in the sinking as reconstructed by the board of inquiry. This image is a screencap from that astonishingly geeky animation.