On her maiden patrol Cavalla, en route to her station in the eastern Philippines, made contact with a large Japanese task force on 17 June.

Cavalla tracked the force for several hours, relaying information which contributed to the United States victory in the Battle of the Philippine Sea (commonly known as the "Marianas Turkey Shoot") on 19–20 June 1944.

A month out on her fifth patrol, the submarine sighted HMS Terrapin, damaged by enemy depth charges and unable to submerge or make full speed.

She joined the fleet units entering Tokyo Bay 31 August, remained for the signing of the surrender on 2 September, then departed the next day for New London, arriving 6 October 1945.

The conversion included removal of two bow torpedo tubes, along with remodeling the original conning tower and bridge into the sail visible today.

Her new sonar made Cavalla valuable for experimentation, and she was transferred to Submarine Development Group 2 on 1 January 1954, to evaluate new weapons and equipment, and to participate in fleet exercises.

She also cruised to European waters several times to take part in NATO exercises, and visited Norfolk, Va., for the International Naval Review (11–12 June 1957).

[10] In November, 1961, Cavalla was ordered to Puerto Rico and provided electrical power via umbilical connection to USS Thresher (SSN-593) which had suffered a diesel generator failure while the nuclear reactor was shut down.