(SS54: dp. 348 (surf.), 414 (subm.); l. 1473; b. 159; dr. 126; s. 13 k. (surf.), 11 k. (subm.); cpl. 25; a. 4 18 tt.; cl. N1)
N2 (SS54) was laid down 29 July 1915 by Seattle Construction and Drydock Co.; launched 16 January 1917; sponsored by Mrs. Whitford Drake; and commissioned 26 September 1917, Lt. Hugh C. Frazer in command.
After fitting out and conducting sea trials in Puget Sound, N2 departed the Navy Yard 21 November 1917, and sailed for San Francisco in company with her sister ships N1 and N3. Upon arriving at San Francisco, she was ordered to proceed to the East Coast via the Panama Canal, for assignment to the Submarine Force, U.S. Atlantic Fleet. She arrived at New London 7 February 1918 and almost immediately began to patrol along the New England Coast, guarding against enemy submarines. Operating in this area for the remainder of the war, N2 helped keep the sea lanes open.
Following the end of World War I, N2 continued her operations out of New London, serving as a training ship for the Submarine School. Beginning in late May 1921, the submarine also tested experimental Navy weapons, such as a radio controlled torpedo, and evaluated its potential value in modern combat. Placed in reduced commission 22 April 1922, N2 continued her training and experimental duties at New London. On 11 October, she aided tanker Swift Star, grounded on the southern end of Block Island. She remained in active service until decommissioned 30 April 1926 at Philadelphia Navy Yard. Struck from the Naval Vessel Register 18 December 1930, N2 was scrapped in early 1931.