Gray Lady Down

Captain Paul Blanchard (Heston) is on his final submarine tour before promotion to command of a submarine squadron (COMSUBRON) The submarine, USS Neptune, is struck by a Norwegian freighter en route to New York in heavy fog. With the engine room flooded and its main propulsion disabled, the Neptune sinks to a depth of 1,450 feet (442 meters or approx. 241.6 fathoms) on a canyon ledge above the ocean floor. A small experimental submersible, Snark, is brought in to assist with the rescue.