The Japanese submarine was among the largest submarines of World War II, able to carry aircraft and could travel one-and-a-half times around the world without needing to refuel.
The I-400 was one of five Japanese submarines captured by the U.S. Navy at the end of World War II and sent to Hawaii for examination.
American forces lost the I-400 whose discovery was announced this week after they deliberately scuttled it in 1946 to avoid the technology falling into Soviet hands.
The submarine was found in August, but the laboratory didn't notify the public until after informing the U.S. State Department and the Japanese government, the university said.
Underwater aircraft carriers
The Sen Toku I-400-class Imperial Japanese Navy submarines were submarine aircraft carriers able to carry three Aichi M6A Seiran aircraft underwater to their destinations. They were designed to surface, launch their planes, then quickly dive again before they were discovered. They also carried torpedoes for close-range combat. The I-400-class was designed with the range to travel anywhere in the world and return.