The submarine Cachalot was laid down at Portsmouth Navy Yard on 21 October 1931 and completed on 1 March 1934. She had six 21-inch torpedo tubes and a 3-inch anti-aircraft gun. Her displacement was 1,110 tons, length overall 272 feet and beam 25 feet. She had a complement of 52 men. On 7 December she was moored at the southern end of Ten Ten Pier.
See also: Ten Ten Pier