(SS-125: dp. 854 (surf.), 1,062 (subm.) ;l. 219'3"; b. 20'8"; dr. 15'11"; s. 14.5 k. (surf.), 11 k. (subm.); cpl. 38; a. 4 21" tt., 1 4"; cl. S-1)
S-20 (SS-125) was laid down on 15 August 1918 by the Bethlehem Shipbuilding Corp., Quincy, Mass.; launched on 9 June 1920; sponsored by Miss Anne Claggett Zell; and commissioned on 22 November 1922, Lt. John A. Brownell in command.
In addition to duty in northeastern points out of New London, Connecticut, from 1922 into 1929, the new submarine visited Coco Solo, C.Z., in March 1923; served at St. Thomas, Virgin Islands, in February 1924; and operated in the Panama Canal area from January through April 1926. S-20 visited Kingston, Jamaica, from 20 to 28 March 1927, and served again in the Panama Canal area from 17 April 1929 into November 1930. Departing Coco Solo on the 7th, S-20 arrived at Pearl Harbor on 7 December that year. Following duty there, she sailed on 20 February 1932 and, from March of that year into April 1933, served at Mare Island. Later, she operated mainly at San Diego into 1934. Departing San Diego on 15 March, S-20 returned to New London on 28 October. From then into December 1941, she operated there as part of a test and evaluation division. During this period, she visited Guantanamo Bay in February and March 1938; served in the Panama Canal area from January into March 1939; and visited Guantanamo again in February 1940.
From December 1941 into July 1945, S-20 continued to operate from New London. Her operations were off New England and often included training activities at Casco Bay, Maine. Departing New London on 2 July 1945, S-20 was decommissioned on the 16th at Philadelphia. Her name was struck from the Navy list on the 25th. She was sold on 22 January 1946 to North American Smelting Co., Philadelphia, Pa., for scrapping.