April 10 is the 50th anniversary of the disappearance of The Thresher submarine.

At 9:18 a.m. on April 10, 1963, sonar operators aboard the U.S. Navy submarine rescue ship Skylark, which was accompanying the nuclear attack submarine Thresher, heard a chilling sound “like air rushing into an air tank,” and Thresher was no more. Its deep-dive trials southeast of Cape Cod, Massachusetts, had come to a cataclysmic end and all 129 men aboard perished in 8,400 feet (2,560 meters) of water.

Phil Ochs wrote a song about it.

I still prefer his song about another submarine lost at sea, The Scorpion, which went down in 1968 somewhere near the Azores: