USS Marlin (SS-205), a Mackerel-class submarine, was the first ship of the United States Navy to be named for the marlin, a large game fish. Marlin and her near-sister Mackerel (designed and built by the Electric Boat Company) were prototype small submarines, which the Navy was exploring to replace the aging S-class submarines. References differ as to whether Marlin had a direct drive propulsion system or diesel-electric drive.