I-400 was an Imperial Japanese Navy Sentoku-type submarine commissioned in 1944 for service in World War II. Capable of carrying three two-seat Aichi M6A1 "Seiran" float-equipped torpedo bombers, the Sentoku-class submarines were built to launch a surprise air strike against the Panama Canal. Until 1965, the Sentaku-type submarines—I-400 and her sister ships I-401 and I-402 —were the largest submarines ever commissioned.
U.S. Navy personnel inspect I-400′s aircraft hangar after World War II.
U.S. Navy personnel examine I-400′s deck gun at Yokosuka, Japan, on 14 October 1945.
The officers of I-400, photographed in front of her aircraft hangar after her surrender to the U.S. Navy in August 1945.
The I-400-class submarine Imperial Japanese Navy (IJN) submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic missile submarines in the 1960s. The IJN called this type of submarine Sentoku type submarine . The type name was shortened to Toku-gata Sensuikan . They were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat.
I-401, with its long plane hangar and forward catapult
The Aichi M6A Seiran
Officers of I-400 in front of the plane hangar, photographed by the US Navy following the surrender of the submarine at sea, one week after the end of hostilities.
Members of the US Navy inspecting the plane hangar of I 400.
