SS Mission Santa Ynez was a Type T2-SE-A2 tanker built for the United States Maritime Commission during World War II.

[2] Mission Santa Ynez was laid down 9 September 1943 under a Maritime Commission contract by Marinship Corporation, Sausalito, California; launched 19 December 1943; sponsored by Mrs. Ralph K. Davies; and delivered 13 March 1944.

Taken over by the newly created Military Sea Transportation Service 1 October 1949 she was redesignated USNS Mission Santa Ynez (T-AO-134).

Chartered to Mathiasens Tanker Industries, Inc., for operations, she entered the Maritime Administration's Suisun Bay Reserve Fleet on 6 March 1975.

Towed from the Maritime reserve Fleet at Suisun Bay, California on 31 March 2010, headed for dismantling in Texas via the Panama Canal.