The long search to find the hulk of the atomic submarine "Thresher" is led by the bathyscaph "Trieste" and the specially-equipped "Mizar" in the Atlantic off Boston. Remarkable underwater cameras succeed in locating and photographing the wreckage, solving part of the mystery, just where the "Thresher" rested. Still unanswered: the cause of the disaster. Research ships in the Atlantic Ocean looking for the 'Thresher'. The 'Thresher" Submarine diving in the Atlantic Ocean. Newly developed camera equipment being lowered into the ocean. Underwater shots of the "Thresher" Tail section. Capitan sitting in the cabin, looking at a monitor smoking a pipe.