[4] During her shakedown cruise out of New London, Connecticut, Cochino visited Newport, Rhode Island, 12–15 September 1945, then sailed for the Panama Canal Zone, on 3 October.

Then, following a visit to St. Thomas, Virgin Islands, 18–20 May, Cochino sailed to conduct simulated attacks upon ships of the 8th Fleet, proceeding then to Key West, upon conclusion of those evolutions.

Shifting to the Naval Ammunition Depot, at Fort Mifflin, upon completion of that yard period, she conducted deep diving tests on 21 June, in the waters of the Baltimore Canyon, at 38°08′N 73°49′W / 38.133°N 73.817°W / 38.133; -73.817, tended by the submarine rescue vessel Tringa, after which time she returned to Philadelphia Naval Shipyard, remaining there until 3 July.

[4] After visiting Miami, from 25–28 October 1947, Cochino operated with the 2nd Task Fleet near Bermuda, through mid-November, after which time she returned to her homeport for upkeep through mid-January 1948.

Work in the Key West operating area or upkeep in port involved the boat until 31 January, when she sailed for New Orleans, for Mardi Gras festivities, from 2–11 February.

Toward the end of that period, on 26 April 1948, while conducting a submerged exercise at a 60 ft (18 m) depth, Cochino collided with the fleet tug Salinan.

[4] In August 1949, Cochino and Tusk sailed along the Kola Peninsula to determine whether the Soviet Union had detonated an atomic bomb.

The huge waves slammed the submarine's snorkel so violently, and jolted the boat so severely, that the pounding caused an electrical fire and battery explosion, followed by the release of deadly hydrogen gas.

Cochino's only fatality was a civilian from the Bureau of Ships, technician Robert W. Philo, swept overboard by an icy wave.