(SS68: dp. 520.6 (surf. n.), 629 (subm.); l 1724; b. 18 ¼; s. 14 k. (surf.), 10.5 k. (subm.); a. 13, 4 18 tt.; cl. O1).
O7, was laid down 14 February 1917 by the Fore River Shipbuilding Co., Quincy, Mass.; launched 16 December 1917; sponsored by Mrs. Constance Sears; and commissioned 4 July 1918, Lt. Comdr. F. C. Sherman, in command.
During the final stages of World War I, O7 operated out of Philadelphia on coastal patrol from Cape Cod to Key West. On 2 November she departed Newport with a 20-sub contingent bound for European waters; however, the Armistice was signed before the ships reached the Azores, and they returned to the United States.
In 1919, O7 reported to the newly established submarine school at New London to train there for the next decade. In 1924 she went to Coco Solo for maneuvers and was reclassified a 2nd line submarine 25 July 1924. Returning to New London, she reverted to 1st line 6 June 1928. In January 1930 she joined her sister ships in a run to Portsmouth, N.H., thence back to New London in February. After returning from Washington, D.C. in July, she continued operations at New London. She sailed to Philadelphia 23 February 1931 and decommissioned there 1 July 1931.
After a decade in mothballs, O7 was recalled to active duty and recommissioned at Philadelphia 12 February 1941. She reported to New London in May and trained sub crews there until the end of World War II. O7 was decommissioned 2 July 1945; struck from the Navy Register 11 July 1945; and sold to North American Smelting Co. of Philadelphia 22 January 1946.