The USS Lapon (SS-260) was a Gato-class submarine constructed by the Electric Boat Company in Groton, Connecticut, with her keel laid on 21 February 1942. She was launched on 27 October 1942 and commissioned into the U.S. Navy on 23 January 1943. As a Gato-class vessel, she featured the typical design characterized by a streamlined hull suitable for extended underwater and surface operations. Lapon’s service history during World War II was marked by aggressive patrols and notable combat achievements in the Pacific Theater. After initial trials and training in Long Island Sound, she departed for the Pacific in May 1943, arriving at Pearl Harbor. Her first war patrol began in June 1943, in which she operated in the Sea of Okhotsk and the Sea of Japan, becoming part of the first U.S. submarines to penetrate the heavily mined straits into the Sea of Japan. Throughout her patrols, she encountered challenges such as thick fog and radar issues but succeeded in sinking multiple enemy vessels, including cargo ships like Taichu Maru, Toyokuni Maru, Nichirei Maru, Hokuroku Maru, Wales Maru, Bizen Maru, Kyodo Maru No. 36, and Ejiri Maru. Lapon’s patrols extended to the South China Sea, where she engaged convoy traffic, sinking several more ships, including Shun Yuan and Hokki Maru. She also participated in lifeguard duties, rescuing aircrew during air strikes and providing reconnaissance to support Allied operations, notably during the invasion of the Philippines. Her combat record was distinguished, credited with sinking a total of 53,443 tons of Japanese shipping, and she earned the Navy Unit Commendation for her outstanding patrols. After the war, Lapon was decommissioned in 1946 but was later recommissioned in 1957, only to be decommissioned and transferred to Greece later that year as Poseidon (S-78). She remained in service with the Greek Navy until 1976, primarily used as a spare parts source for her sister ships. Her wartime service and her transition to allied service highlight her maritime significance as one of the successful and decorated submarines of the U.S. Navy during World War II.

This description has been generated using GPT-4.1-NANO based on the Vessel's wikidata information and then modified by ShipIndex.org staff.