The I-400 Class was a series of submarines built by the Imperial Japanese Navy during World War II. These submarines were notable for their large size and unique design, allowing them to carry and launch aircraft. Each I-400 submarine could carry up to three Aichi M6A Seiran floatplanes, which were intended for long-range missions. The I-400 Class submarines were the largest of their kind at the time, measuring over 400 feet in length. They were equipped with advanced technology for their era, including a snorkel system that allowed them to operate submerged for extended periods. Despite their capabilities, only a few were completed before the war ended.