USS S-15 at Bridgeport, Connecticut, on 3 January 1921, twelve days before her commissioning.
History
United States
Name	USS S-15
Builder	Lake Torpedo Boat Company
Laid down	13 December 1917
Launched	8 March 1920
Sponsored by	Mrs. Simon Lake
Commissioned	15 January 1921
Decommissioned	26 April 1935
Recommissioned	3 January 1941
Decommissioned	11 June 1946
Fate	Sold for scrap, 4 December 1946
General characteristics
Class and type	S-class submarine
Displacement	876 long tons (890 t) surfaced 1,092 long tons (1,110 t) submerged
Length	231 ft (70 m)
Beam	21 ft 10 in (6.65 m)
Draft	13 ft 1 in (3.99 m)
Speed	15 knots (17 mph; 28 km/h) surfaced 11 knots (13 mph; 20 km/h) submerged
Complement	38 officers and men
Armament	1 × 4 in (100 mm)/50 deck gun 4 × 21 inch (533 mm) torpedo tubes

USS S-15 (SS-120) was a second-group (S-3 or "Government") S-class submarine of the United States Navy. Her keel was laid down on 13 December 1917 by the Lake Torpedo Boat Company in Bridgeport, Connecticut. She was launched on 8 March 1920 sponsored by Mrs. Simon Lake, and commissioned on 15 January 1921.

Attached to SubDiv 18, S-15 departed New London, Connecticut, on 31 May 1921, and sailed via the Panama Canal, California, Hawaii, and Guam to the Philippines. She arrived at Cavite, Luzon, on 1 December. In 1922, she sailed from Cavite on 11 October, visited Hong Kong from 14 October to 28 October, and returned to Cavite on 1 November. Sailing from Manila on 15 May 1923, S-15 visited Shanghai, Yantai, and Qinhuangdao before returning via Wusong and Amoy to Cavite on 11 September. In the summer of 1924, she again visited China and returned to Olongapo on 23 September.

Departing Cavite on 29 October, she arrived at Mare Island Naval Shipyard, California, on 30 December. Remaining at Mare Island in 1925 and 1926, she operated along the west coast through 1927. From February 1928 into 1935, S-15 served in the Panama Canal area, although she visited Baltimore, Maryland, from 15 May to 5 June 1933. She departed Coco Solo on 11 January 1935 for Philadelphia, Pennsylvania, where she decommissioned on 26 April 1935.

S-15 was recommissioned on 3 January 1941 at Philadelphia. Following voyages to Bermuda, she operated at Saint Thomas, United States Virgin Islands, from 31 October to 9 December 1941; in the Panama Canal area from January 1942 into December 1943; at Guantanamo Bay through May 1944; in the Panama Canal area from June through September; at Trinidad for the rest of the year; and at Guantanamo from January into March 1945.

S-15 departed Guantanamo on 23 March 1945 and reported at New London for inactivation. She was decommissioned on 11 June 1946 at Philadelphia and was struck from the Naval Vessel Register. On 4 December 1946 she was sold for scrapping to the Potomac Shipwrecking Company of Maryland.

Following the decommissioning of S-23 in November 1945, S-15 was the last S Class submarine in commission. Following the decommissioning of O-4 in September 1945, S-15 was the oldest submarine in commission in the U.S. Navy.

S-15 was one of the only five submarines (along with her sisters S-14, S-16, S-17 and S-48) built by the Lake Torpedo Boat Company to see service in World War II. She was last submarine built by the Lake Torpedo Boat Company in service when she was decommissioned in June 1946.

• American Defense Service Medal
• American Campaign Medal
• World War II Victory Medal

 This article incorporates text from the public domain Dictionary of American Naval Fighting Ships. The entry can be found here.

• Photo gallery of S-15 at NavSource Naval History