USS Sailfish (SS-192), was a US Sargo-class submarine, originally named Squalus. As Squalus, the submarine sank off the coast of New Hampshire during test dives on 23 May 1939. The sinking drowned 26 crew members, but an ensuing rescue operation, using the McCann Rescue Chamber for the first time, saved the lives of the remaining 33 aboard. Squalus was salvaged in late 1939 and recommissioned as Sailfish in May 1940.

The Sargo-class submarines were among the first United States submarines to be sent into action after the Japanese attack on Pearl Harbor, starting war patrols the day after the attack, having been deployed to the Philippines in late 1941. Similar to the previous Salmon class, they were built between 1937 and 1939. With a top speed of 21 knots, a range of 11,000 nautical miles (20,000 km), and a reliable propulsion plant, along with the Salmons they were an important step in the development of a true fleet submarine. In some references, the Salmons and Sargos are called the "New S Class", 1st and 2nd Groups.