USS Peto (SS-265), a Gato-class submarine, was a ship of the United States Navy named for the peto, a sharp-nosed tropical fish of the mackerel family.

Peto was laid down on 18 June 1941 by the Manitowoc Shipbuilding Company at Manitowoc, Wisconsin; launched on 30 April 1942 sponsored by Mrs. E. A. Lofquist; and commissioned on 21 November 1942, Lieutenant Commander William T. Nelson in command.

Late in December 1942, Peto decommissioned, was loaded on a barge, and departed Manitowoc for New Orleans, Louisiana, the first submarine to traverse the mid-western waterways to reach New Orleans and the sea from the building yards. This was done because the Chain of Rocks Waterway as well as some of the passages near Chicago were only 9 feet (2.7 m) deep, whereas the minimum draft of the submarine was 12 feet (3.7 m). Peto recommissioned, completed fitting out and shakedown, transited the Panama Canal, and arrived at Brisbane, Australia, on 14 March 1943.

Peto departed Brisbane for her first war patrol on 2 April 1943. She reconnoitered Greenwich Island for shipping on 13 April without finding any targets. That night she proceeded toward the equator to cover the Truk-Kavieng shipping route, arriving on station the next day. A southbound Truk-Rabaul convoy came into view on the morning of 17 April, consisting of two destroyers, two medium cargo ships, and one small auxiliary ship. However, before Peto attacked, the trailing destroyer detected her and forced her to dive. She withstood nine depth charges without damage.

On 5 May, she made a night attack conducted by sound and radar alone, firing three torpedoes at a target for one possible hit. After patrolling off Cape Oxford on New Britain, Peto headed for Brisbane on 20 May 1943.

Peto departed on her second war patrol on 10 June 1943. On 29 June, she fired two torpedoes at a small auxiliary. One torpedo hit near the bow, breaking the ship in two. On 7 July, she sighted an eastbound tanker similar to Nippon Maru with two escorting destroyers. Peto maneuvered and fired three torpedoes; two hits causing severe damage. She returned to Brisbane on 4 August 1943.

On 1 September 1943, Peto set out on her third war patrol, assigned a patrol area north of the Bismarck Archipelago. After reconnoitering Nauru Harbor, she patrolled the route between Truk and Nauru for five days without contact. On 9 September, an Allied maritime patrol aircraft mistakenly attacked her with a depth charge 310 nautical miles (570 km; 360 mi) north-northeast of Buka on Bougainville Island in the Solomon Islands at 03°49′S 158°26′E / 3.817°S 158.433°E / -3.817; 158.433. The depth charge missed by a wide margin, and Peto submerged to 200 feet (61 m) and avoided damage.

Peto moved to the Truk-Kavieng-Rabaul traffic routes on 20 September, and two days later, sighted five escorted ships headed toward Rabaul. She lost her attack chance at the last moment when the Japanese ships made a radical change of course. While Peto attempted to close for a night attack, an alert escort only 7,000 yd (6,400 m) away detected her. The Japanese ship opened fire on her, forcing her to crash-dive.