advexontube.com Seosan TV DOCUMENTARY HD ( WORLD BEST DOCUMENTARIES AROUND THE WORLD ) The I-400-class submarine or Imperial .\rbr\rbr\rbr\rbrImperial Japanese Navy submarines were the largest submarines of World War II and remained the largest ever built until the construction of nuclear ballistic .\rbr\rbrA World War Two Japanese submarine, that had been lost since 1946, is discovered off the coast of a Hawaiian island. A World War II Imperial Japanese Navy .