USNS Mission San Francisco (T-AO-123) was a Mission Buenaventura-class oiler that served in the United States Navy. The ship was originally intended as USS Contoocook (AO-104) for the U.S. Navy but her acquisition was canceled. The ship, a Type T2-SE-A3 tanker, was completed as SS Mission San Francisco and delivered after the end of World War II. The tanker was acquired by the U.S. Navy in 1947 as USS Mission San Francisco (AO-123), but was transferred to the Military Sea Transport Service (MSTS) upon its creation in 1949. During a second stint with the MSTS that began in 1954, Mission San Francisco collided with the freighter Elna II in the Delaware River coast and was declared unsalvageable by the U.S. Navy. The ship was one of two U.S. Navy vessels named for the Franciscan mission of Sa