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.
Japanese submarine I-60
The Japanese submarine "I-60" was a cruiser submarine of the KD3B sub-class built for the Imperial Japanese Navy (IJN) during the 1920s. The boat supported Japanese forces during the Dutch East Indies campaign in early 1942 until she was sunk by a British destroyer on 17 January.