Following fitting out and initial training along the California coast (which took her as far south as San Diego), Wahoo departed Mare Island on 12 August for Hawaii.

On 23 August 1942 Wahoo got underway for her first war patrol, seeking Japanese shipping in waters west of Truk, particularly in the area between the Hall Islands and the Namonuito Atoll.

The first was Chiyoda (listed as a seaplane tender, she was in fact a mother ship to midget submarines[5]), sailing without escort; Wahoo proved unable to reach a firing position.

On 30 November, the submarine spotted smoke at a distance of 8,000 yd (7,300 m); it was a lightly loaded freighter or transport with an escorting destroyer on the port bow.

Rather than use the new SJ radar to mount a second attack, which might well sink the freighter (then stopped to pick up survivors[6]), and possibly even the destroyer, Wahoo let them go on a northeasterly course and moved into a new area.

On 24 January 1943, Wahoo dove 2 nmi (2.3 mi; 3.7 km) north of Kairiru Island and proceeded around the western end to penetrate Victoria Bay.

[16]"Apparently her skipper had lost his nerve when he saw our last torpedo heading toward him and put the rudder over to try to miss it, and by swinging himself broadside to it he signed the destroyer's death warrant.

Fukuei Maru was listing badly to starboard and sinking by the stern; the second ship was headed directly for Wahoo, at a slow speed.

The second torpedo hit, but the target kept coming and forced the submarine to turn hard to port at full speed to avoid being rammed.

Wahoo headed for the transport and fired a bow tube; the torpedo passed directly under the middle of the ship but failed to explode.

Wahoo decided to let these two ships get over the horizon, while she surfaced to charge her batteries and attack the shipwrecked Japanese now sitting in about twenty lifeboats.

Vice Admiral Charles A. Lockwood, then COMSUBPAC, asserts that the survivors were army troops and turned machinegun and rifle fire on Wahoo while she maneuvered on the surface, and that such resistance was common in submarine warfare.

The report[22] for Patrol Three described the events as follows:At 1115 ...Decided to let these two ship[s] get over the horizon while we surfaced to charge batteries and destroy the estimate[d] twenty troop boats now in the water.

She surfaced and the convoy scattered, but before Morton could have the deck gun manned a Japanese destroyer escort charged out of a rain squall onto the scene, forcing Wahoo to run for it.

[30] The next day, Wahoo sighted Fais Island, and her plan to shell a phosphorite refinery was scrapped due to the untimely appearance of an inter-island steamer.

On 23 February 1943, Wahoo got underway for Midway Island, where she arrived four days later, topped off her fuel tanks, and headed for her patrol area.

The freighter tried to ram her, but Wahoo maneuvered clear, and then continued firing at the target, setting her ablaze from stem to stern, and leaving her dead in the water.

Wahoo surfaced, transited the Collnett Strait, and headed home, concluding a war patrol which topped the record to date in number of ships sunk.

Three days later, Wahoo sighted two ships hugging the shoreline on a northerly course, 12 nmi (14 mi; 22 km) off the Benten Saki coast, and dove.

The submarine submerged 1 nmi (1.2 mi; 1.9 km) off Kobe Zaki and sighted a three-ship convoy consisting of two escort vessels and a large naval auxiliary.

Radar picked up two targets, soon identified as a large tanker and a freighter in column, evidently making the night run between ports without an escort.

The second hit under the bridge with a dull thud, much louder than the duds heard only on sonar but lacking the "whacking" noise which accompanies a wholehearted explosion.

On 19 August, the submarine sighted a ship and commenced tracking, but she withheld her fire when her crew recognized the flag as Soviet (an ally of the United States at the time).

On 25 September 1943 the Taiko Maru was torpedoed in the Sea of Japan; mistakenly credited to the USS Pompano (SS-181), she was apparently sunk by Wahoo.

[33][34] On 5 October, the Japanese news agency Domei announced to the world that a steamer, the 8,000 long tons (8,128 t) Konron Maru, was sunk by an American submarine off the west coast of Honshū near Tsushima Strait, with the loss of 544 lives.

The sinking of Konron Maru enraged the Japanese navy, and the Maizuru Naval District ordered a 'search and destroy' operation for US submarines.

Sawfish had been depth-charged by a patrol boat while transiting the strait two days before, and the enemy's antisubmarine forces were on the alert; their attacks fatally holed Wahoo, and she sank with all hands.

Beginning in 1995, the Wahoo Project Group (an international team of Americans, Australians, Japanese, and Russians, and led by a relative of Commander Morton) searched for her based on the available evidence.

[35] In 2005, electronic surveys in the region yielded what turned out to be a U.S. Gato-class submarine in the Strait; in July 2006, the Russian team "Iskra" investigated the site which contributed further evidence of location of Wahoo.

On 31 October 2006, the U.S. Navy confirmed that the images provided by the "Iskra" team are of Wahoo, the wreckage lying intact in about 213 ft (65 m) of water in the La Pérouse (Soya) Strait.