T-1-class submarine

The T-1 class submarines were a pair of submarines built for the United States Navy in the early 1950s for use in training submarine personnel and testing submarine equipment. Both submarines of the class served in these roles for over 19 years.

Design and construction
The T-1-class were among the smallest operational submarines ever built for the United States Navy. The first unit was planned as an experimental auxiliary submarine with hull number AGSS-570, but instead was built as the training submarine USS T-1 with hull number SST-1. Her sister ship, USS T-2, was planned as SST-2 from the beginning.

Both submarines were constructed by the Electric Boat Division of the General Dynamics Corporation at Groton, Connecticut, in 1952-1953.

Service history
Both submarines entered service in 1953 and were renamed in 1956, T-1 becoming USS Mackerel (SST-1) and T-2 becoming USS Marlin (SST-2). Both operated primarily in Florida and Caribbean waters to train submarine personnel, serve as targets for sonar and antisubmarine warfare training, and test submarine equipment. They were decommissioned simultaneously in a combined ceremony in 1973.

USS Mackerel (SST-1), ex-USS T-1, ex-AGSS-570
USS Mackerel (SST-1), planned as AGSS-570, was commissioned as T-1 (SST-1) in October 1953 and decommissioned in January 1973. A highlight of her career was testing of equipment for the NR-1 Deep Submergence Craft in 1966-1967. Mackerel was sunk as a target in 1978.

USS Marlin (SST-2), ex-USS T-2
USS Marlin (SST-2) was commissioned as USS T-2 (SST-2) in November 1953 and decommissioned in January 1973. Donated as a museum ship in August 1973, she was assigned on 20 August 1974 to go on display at Freedom Park in Omaha, Nebraska.