Draft markings on the topside rudder of Thresher. Part of the port stern plane of the sunken sub can be seen in the foreground. The bit of line on the right is connected to the underwater camera-magnetometer sled towed by USNS Mizar. The original photograph bears the date October 1964. Quoted text is from the caption released with that print. Official U.S. Navy Photograph, from the collections of the Naval History and Heritage Command.