Zothecula writes: Until the 1960s, Japan's three I-400-class subs were the largest submarines ever built. They were so large, in fact, that they could each carry and launch three Aichi M6A Seiran amphibious aircraft. The idea was that the submarines could stealthily bring the planes to within striking distance of US coastal cities, where they could then take off and conduct bombing runs. Now, for the first time since it was scuttled at the end of World War II, one of the sunken subs' aircraft hangars has been photographed. The M6A on display at the Air and Space Museum's Udvar-Hazy Center is worth seeing, if you get a chance.