Last Thursday, researchers annoucned that they have found two Japanese subs which were sunk over 63 years ago. The subs were destined to attack the US and the Panama Canal, with one even capable of carrying and launching airplanes. From the NYTimes:
The submarines, among five that were captured by American forces at the end of the war and taken to Pearl Harbor for study, were found off Oahu at a depth of about 2,600 feet using submersibles from the Hawaii Undersea Research Laboratory, which is financed by the National Oceanic and Atmospheric Administration and located at the University of Hawaii at Manoa. The five were towed to sea in 1946 and torpedoed, and the researchers said one probable reason for that was to avoid having to share any of the technology with the Russian military.
One of the Japanese craft, the I-201, was capable of speeds of about 20 knots while submerged, making it among the fastest diesel submarines ever made. Like other Japanese subs, it had a rubberized coating on the hull, an innovation intended to make it less apparent to sonar or radar.
The other, the I-14, was much larger and slower and designed to carry two small planes, Aichi M6A Seirans. The aircraft, which had folding wings and tails and could carry a torpedo or 1,800-pound bomb, were housed in watertight hangars inside the submarine. They could be brought onto the deck and launched by a catapult. (The only existing Seiran is in the hands of the Smithsonian.)