The Regulus missile submarines were a group of submarines operated by the United States Navy capable of carrying the Regulus cruise missile. Between 1959 and 1964, a total of five boats were used to undertake the first submarine-based nuclear deterrent patrols by the United States. Regulus submarines were used for this task until 1964, when sufficient ballistic missile submarines carrying the Polaris ballistic missile became available.

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.