Submarines of the Imperial Japanese Navy
Imperial Japanese Navy (IJN) submarines formed by far the most varied fleet of submarines of World War II, including manned torpedoes ("Kaiten"), midget submarines ("Kō-hyōteki", ), medium-range submarines, purpose-built supply submarines (many used by the Imperial Japanese Army, see Type 3), fleet submarines (many of which carried an aircraft), submarines with the highest submerged speeds of the conflict ("Sentaka" ), and submarines able to carry multiple bombers (World War II's largest submarine, the Sentoku ). They were also equipped with the most advanced torpedo of the conflict, the oxygen-fuelled Type 95 (which are sometimes confused with the famed Type 93 Long Lance torpedo).
Scuttling
To prevent a Soviet inspection team from examining surrendered Imperial Japanese Navy submarines after World War II, the United States Navy conducted Operation Road's End, in which it scuttled 24 of the submarines in the East China Sea off Fukue Island on 1 April 1946. Nine more Japanese submarines followed on 5 April, and another six went down by early May. In addition, U.S. Navy submarines sank four surrendered Japanese submarines as targets in the Pacific Ocean near Hawaii in May and June 1946, and the Royal Australian Navy sank six or seven (sources differ) surrendered Japanese submarines in the Seto Inland Sea on 8 May 1946 in Operation Bottom.