Submarine I-402 of the Imperial Japanese Navy was one of three completed Sen Toku I-400 class submarine aircraft carriers during World War II and world’s largest submarine until 1965. She was laid down in July, 1945. Their initial purpose was to to carry aircraft which would be used to destroy the Panama Canal. An order was made to build a total of 18 submarines but only 3 (I-400, I-401 and I-402) would be completed before the war ended.
The Americans never learned of the existence of the I-400-class submarines until their crews surrendered. I-402 and her sister ships were studied by the United States Navy at Sasebo Bay, Japan between October, 1945 and April, 1946.
After the Soviet-Union planned to send inspectors to study these captured Japanese submarines, the U.S. Navy decided to keep the technology out of Soviet hands and launched Operation Road’s End on April 1, 1946. The I-402 and 23 other submarines were scuttled near the Goto Islands in Nagasaki, the I-402 was used as target practice for the USS Larson. The 24 submarines have now been found last Friday, reports the Japan Times, by the Japanese Coast Guard.
The I-400 and I-401 were scuttled near Hawaii.