Submarines of the Imperial Japanese Navy
Imperial Japanese Navy submarines originated with the purchase of five Holland type submarines from the United States in 1904. Japanese submarine forces progressively built up strength and expertise, becoming by the beginning of World War II one of the world's most varied and powerful submarine fleets.
Imperial Japanese Navy in World War II
Early models were not very maneuverable under water, could not dive very deep, and lacked radar. Later in the war, units fitted with radar were in some instances sunk due to the ability of US radar sets to detect their emissions. For example, sank three such in the span of four days. After the end of the conflict, several of Japan's most innovative and advanced submarines were sent to Hawaii for inspection in "Operation Road's End" ("I-400", "I-401", "I-201" and "I-203") before being scuttled by the U.S. Navy in 1946 when the Soviets demanded access to the submarines as well.