At A. Uttrick peered through his binoculars from the deck of the minesweeper USS Condor. By the pale light of a waning moon, the American sailor spied something unusual piercing the glassy skin of the Pacific Ocean less than two miles south of the entrance to Pearl Harbor. Credit: National Museum of the Pacific War. Hours before swarms of enemy aircraft descended out of the blue in a sneak attack upon the United States naval base on Oahu, five Japanese midget submarines were already lurking beneath the ocean surface to join in the assault on Pearl Harbor. The Japanese navy considered the foot-long miniature submarines to be their secret weapon. Carrying two men and two torpedoes that had double the explosive charge of those borne by Japanese bombers, the battery-powered midget submarines could glide at 19 knots and operate in the waters of Pearl Harbor that were too shallow for conventional submarines.
How The Royal Navy's X-Class Midget Subs Helped Make D-Day Possible
The HA. 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 Type 92 periscope was installed later in May In November , HA.
Japanese mini Submarines at Pearl Harbor
As part of the attack on Pearl Harbor on December 7, , the Imperial Japanese Navy sent an attack group of submarines to surround Oahu and sink ships attempting to flee. Five of the submarines carried top-secret "mini submarines. They were to surface and fire their torpedoes during the aerial attack. Then, they would dive and escape the harbor, and rendezvous with their "mother submarines," again under cover of darkness the night of December 7. While the aerial attack was devastating, the mini submarines failed in their mission.
A midget submarine also called a mini submarine is any submarine under tons,  typically operated by a crew of one or two but sometimes up to 6 or 9, with little or no on-board living accommodation. They normally work with mother ships, from which they are launched and recovered and which provide living accommodation for the crew and support staff. Both military and civilian midget submarines have been built.