6th Fleet (Imperial Japanese Navy)
Despite these advantages, IJN submarines achieved remarkably little during World War II primarily having in hindsight suffered from the antiquated strategy of the Imperial Japanese Navy General Staff, who viewed submarines as little more than scouts whose main role was to locate and shadow enemy naval task forces in preparation for a decisive surface conflict. Maybe the IJN General Staff was slow to change as the submarines were generally slow to dive, easy to track with radar and sonar, difficult to maneuver underwater, and less sturdy than their German U-boat counterparts.
HA. 19 (Japanese Midget Submarine)
The HA. 19 (also known as Japanese Midget Submarine "C" by the US Navy) is a historic Imperial Japanese Navy midget submarine that was part of the Japanese attack on Pearl Harbor on 7 December 1941. This submarine was ordered to enter Pearl Harbor then attack the American warships with its torpedoes and then be scuttled with explosives next to a warship. However, she did not enter the harbor, and was grounded and captured. The submarine was eventually put on display near the submarine squadron at Naval Station Key West, Florida, then moved to the nearby Key West Lighthouse and Military Museum. "HA. 19" is now displayed at the National Museum of the Pacific War in Fredericksburg, Texas.