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

Originally laid down as SS Mission San Gabriel on 31 January 1944 as a Maritime Commission type (T2-SE-A2) tanker hull under Maritime Commission contract (MC hull 1817) by Marine Ship Corporation, Sausalito, California; launched on 17 April 1944, sponsored by Mrs. Ralph Meyers: and delivered on 27 May 1944.

She helped support U.S. forces in Korea until 31 March 1954, when she was taken out of service and mothballed at the San Diego group of the Pacific Reserve Fleet.

Sold to the Hudson Waterways Corporation on 24 June 1966 she was converted into a container ship by Savannah Machine and Foundry and renamed SS Seatrain Delaware, IMO 6621208, on 21 November 1966.

In early 1967, she departed the yards and began her new career carrying containerized cargo for Seatrain Lines between the east and west coasts of the United States and to Puerto Rico.