Recently, the crew of the the Hawaii Undersea Research Laboratory‘s submersible Pisces V announced finding the hull of the Japanese mega-submarine I-400 at a depth of 2,300 feet on the sea floor off Hawaii. The huge submarine survived World War II but was scuttled by the United States in the early days of what would become known as the Cold War to prevent the Soviets from gaining access to what was at the time the most advanced submarine technology in the world.
The I-400 was the largest submarine of its day. At 400′ long, the I-400 and its sister vessels would remain the largest submarines ever constructed until the advent of nuclear ballistic missile submarines in the 1960s. The I-400 was also an aircraft carrier, capable of carrying up to three Aichi M6A Seiran bombers in water-tight hangers. The submarines were intended to attack the Panama Canal among other targets. Thee of the huge submarines were built while two others were under construction at the end of the war. All five were brought to Pearl Harbor following Japan’s surrender.