(YA) This is the story that can be pieced together of the worst submarine disaster in history, during which 129 souls died. The Thresher was a nuclear attack submarine. On April 10, 1963, the Thresher lost radio contact with a nearby submarine rescue ship and disappeared into utter mystery, leaving only an oil slick and bits of cork and plastic. The most probable cause of the sinking was either flooding or loss of propulsion. Considerably less probable are sabotage (other than thorough carelessness), attack by an enemy sub, a collision or the speculation that a crew member went berserk. Nor was a nuclear explosion likely. One of the most hair-raising possibilities was that U.S. industry and shipyards are guilty of poor workmanship, such as faulty welding, faulty radiography and defective castings. The ship's last minutes are only too well described by Polmar, as hardened steel began twisting like taffy and the whole machine imploded. ""In a fraction of a second millions of pounds of water under tremendous pressure smashed into the submarine's hull, twisting portions of it, disintegrating other parts of it along with the lighter materials inside it. Death was instantaneous and painless all inside the submarine."" There is a lot of sombre conjecture here.