I-1 was a J1 type submarine of the Imperial Japanese Navy. She was a large cruiser submarine displacing 2,135 tons and was the lead unit of the four submarines of her class. Commissioned in 1926, she served in the Second Sino-Japanese War and World War II. During the latter conflict she operated in support of the attack on Pearl Harbor, conducted anti-shipping patrols in the Indian Ocean, and took part in the Aleutian Islands campaign and the Guadalcanal campaign. In January 1943, during the Japanese evacuation of Guadalcanal, Operation Ke, the Royal New Zealand Navy minesweeper corvettes HMNZS Kiwi and HMNZS Moa intercepted her, and she was wrecked at Kamimbo Bay on the coast of Guadalcanal after the ensuing surface battle.