After World War II, Bergall served in the United States Pacific Fleet until 1950 and made a cruise in Alaskan waters and a deployment to the Far East.

During her voyage to the Panama Canal Zone, she was near Puerto Rico when a United States Army Air Forces training plane crashed into the sea about 1,000 yards (910 m) away.

While endeavoring to send a follow-up message on 23 September, Bergall had to submerge quickly when a Japanese Yokosuka P1Y (Allied reporting name "Frances") twin-engined bomber approached and dropped a depth charge on her wake.

As Bergall worked toward her assigned patrol station in the South China Sea off Japanese-occupied French Indochina, four more Japanese planes harassed her progress, delaying her arrival off Cap Varella until 29 September 1944.

7 Taiwan Maru picked up ten of Shinshu Maru′s survivors Bergall then moved farther south, cruising along a patrol line near Saigon until 24 October 1944.

On the evening of 13 December 1944, while patrolling in darkness off the southern tip of French Indochina, Bergall sighted two Japanese warships — the heavy cruiser Myōkō and destroyer Ushio — moving away from her at 13 knots (24 km/h; 15 mph).

One landed in her wake close astern and the other, an 8-inch (203 mm) round, pierced Bergall′s forward loading hatch, tearing a large hole in her pressure hull but failing to explode.

Bergall′s crew, believing they had sunk Myōkō, spent the rest of 13 December 1944 extinguishing electrical fires, cleaning up the debris caused by the shell hit, and stuffing the ruined hatch with mattresses to keep out sea spray.

The two submarines traveled nearly 2,000 nautical miles (3,700 km; 2,300 mi) without incident, arriving at Exmouth Gulf on the coast of Western Australia safely on 20 December 1944.

On 7 February 1945, while submerged off Hannai Point, Bergall sighted the Japanese convoy HI-93 off Vân Phong Bay,[7] identifying it as consisting of two tankers guarded by four large escorts.

Surfacing that evening, Bergall learned from the nearby submarine USS Flounder (SS-251) that the Japanese escorts had been driven off by a U.S. Navy PB4Y-1 Liberator patrol bomber.

Following two weeks of repairs alongside the submarine tender USS Griffin (AS-13), Bergall put to sea early in March 1945 for her fourth war patrol.

In company with Blueback and the submarine USS Blenny (SS-324), Bergall proceeded to the coast of French Indochina and took up a lifeguard station off Cape Varella on 7 March 1945.

She stayed there, battling rough seas and dodging packs of fishing boats, until 15 March, when she headed north to rescue four American aviators spotted in a life raft.

She then underwent a refit in drydock which included a hull cleaning and repairs to a rudder that vibrated excessively and which brought her a new surface search radar as well as one 40-millimeter and two 20-millimeter guns.

Unable to attack Japanese ships successfully in this condition, she turned north for Subic Bay, arriving there on 17 June 1945, bringing her fifth war patrol to an end.

She conducted a series of post-overhaul training exercises before passing through the Panama Canal and reporting for duty with the United States Pacific Fleet at Pearl Harbor on 18 December 1945.

Assigned to Submarine Squadron 1, Bergall spent the next year, aside from one cruise to Guam in the Mariana Islands and back, operating locally in Hawaiian waters.

One of the training measures devised to give submarine crews experience in case of such a conflict was the "simulated war patrol," a mission upon which Bergall embarked in April 1947.

Although Iowa enjoyed land-based air cover and tried to throw off her pursuers by several radical course changes, the submarines still achieved four "successful" mock attacks against the battleship, including one by Bergall from a range of only 950 yards (870 m).

In preparation for experiments to be conducted during her second simulated war patrol, Bergall took on board two scientists from Columbia University and installed gravimetry equipment inside her.

Underway from Pearl Harbor on 3 December 1948, Bergall slowly proceeded southwest, diving at 50-nautical-mile (93 km; 58 mi) intervals to take underwater gravity measurements.

During these exercises, her crew discovered that, at least during calm weather, patrol planes could drop sonobuoys near her and vector in supporting destroyers, who successfully "pinned down" the submarine.

On 6 June 1951, she embarked on a training cruise to the West Indies, visiting Guantanamo Bay Naval Base and Havana in Cuba and Port-au-Prince in Haiti before returning to New London on 10 July 1951.

There, between 9 November 1951 and 9 April 1952, shipyard workers installed a new streamlined sail and the air intake and exhaust tubes of the submarine snorkel system, allowing Bergall to operate her diesel engines while submerged at periscope depth.

Over the next six weeks, in between various antisubmarine warfare exercises with units of the Sixth Fleet, she visited ports in Italy and Spain and familiarized herself with the waters of the western Mediterranean.

In addition to her usual routine from New London, Bergall provided target services for the Sound School at Port Everglades, Florida, in May 1956, visited Halifax, Canada, in June 1956, and conducted more development exercises at Bermuda in August 1956.

Underway for her post-overhaul shakedown cruise on 7 June 1957, Bergall headed south to Fort Lauderdale, Florida, for two weeks of operations and target services before returning to New London.

She spent the next seven weeks in the Mediterranean, conducting operations with units of the Sixth Fleet at sea and visiting Piraeus and Patras in Greece, Valletta in Malta, and Catania and Naples in Italy.

She conducted antisubmarine warfare exercises from San Juan, Puerto Rico, and St. Thomas in the United States Virgin Islands until returning to New London on 28 March 1958.