USS Grayling (SS-209) was the tenth Tambor-class submarine to be commissioned in the United States Navy in the years leading up to the country's December 1941 entry into World War II.

After conducting tests and sea trials, she was called upon 20 June 1941 to assist in the search for submarine O-9 (SS-70), which had failed to surface after a practice dive off Isles of Shoals.

Cruising the Northern Gilbert Islands, Grayling failed to register a kill, but gained much in training and readiness, returning to Pearl Harbor on 7 March.

Cruising off the coast of Japan itself, Grayling sank her first ship 13 April, sending the cargo freighter Ryujin Maru to the bottom.

As part of Task Group 7.1, Grayling and her sister submarines were arranged in a fan-like reconnaissance deployment west of Midway Atoll in the Northwestern Hawaiian Islands, helping to provide knowledge of Japanese movements.

During this deployment, 12 U.S. Army Air Forces B-17 Flying Fortress bombers sighted Grayling on 7 June 1942 while she was on the surface, and three of them mistakenly attacked her with a string of twenty 1,000-pound (454 kg) bombs dropped from an altitude of more than 10,000 feet (3,000 m), all of which missed.

[7] As U.S. Navy planners established a submarine blockade of Truk in connection with the U.S. offensive in the Solomon Islands, Grayling began her third war patrol on 14 July 1942 around the Japanese stronghold.

Although attacked by gunfire and six separate depth charge runs by Japanese destroyers, Grayling succeeded on 10 November 1942 in sinking a 4,000-ton cargo ship southwest of Truk.

Grayling left Australian waters on 26 March on her sixth war patrol and cruised in the Tarakan area and the Verde Island Passage.

She made two visits to the coast of the Philippines, delivering supplies and equipment to guerrillas at Pucio Point, Pandan Bay, Panay, 31 July and 23 August 1943.

Cruising in the Philippines area, Grayling recorded her last kill, the passenger-cargo Meizan Maru on 27 August in the Tablas Strait, but was not heard from again after 9 September.