USS Burrfish (SS/SSR-312) was a Balao-class submarine of the United States Navy named for the burrfish, a swellfish of the Atlantic coast. The vessel entered service in 1943 and saw action during World War II and in the postwar era. In 1961 Burrfish was loaned to the Royal Canadian Navy where she served as HMCS Grilse and was used primarily as a training boat from 1961 until 1969.

The Balao class was a design of United States Navy submarine used during World War II, and with 120 boats completed, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences. The most significant improvement was the use of thicker, higher yield strength steel in the pressure hull skins and frames, which increased their test depth to 400 feet (120 m). Tang actually achieved a depth of 612 ft (187 m) during a test dive, and exceeded that test depth when taking on water in the forward torpedo room while evading a destroyer.