USS Squalus was the U.S. Navy submarine that sank off New Hampshire in 1939 and was later renamed USS Sailfish.
On 23 May 1939, Squalus suffered a valve failure during a test dive near the Isles of Shoals. Seawater flooded the submarine’s after compartments, killing 26 crew members, while 33 sailors survived in the forward sections.
The rescue became a landmark in submarine history. Using the newly developed McCann-Erickson rescue chamber, rescuers brought all 33 survivors to the surface over several trips. The submarine was subsequently salvaged, repaired, and recommissioned as USS Sailfish in 1940.
Sailfish later served in the Pacific during World War II. It is often confused with USS Scorpion or USS Thresher, but those submarines were lost in different incidents and were not renamed Squalus.