Type A Ko - hyoteki - class submarine The class was a class of Japan ese midget submarine s ( " Ko - hyoteki " ) used during World War II . They had hull numbers but no names . For simplicity , they are most often referred to by the hull number of the mother submarine . Thus , the midget carried by " イ - 16 " was known as I - 16 ' s boat , or " I - 16tou . " This class was followed by : , , and , the last one better known as . History . Fifty were built . The " A Target " name was assigned as a ruse : If their design was prematurely discovered by Japan ' s foes , the Japanese Navy could insist that the vessels were battle practice targets . They were also called or and other slang names . The first two , " No . 1 " and " No . 2 " , were used only in testing . They did not have conning tower s , which were added to the later boats for stability underwater . " No . 19 " was launched by at Pearl Harbor . Most of the other fifty are unaccounted for , although three were captured in Sydney ( Australia ) , and others in Guam , Guadalcanal , and Kiska Island , accounting for some of the other hull numbers . The submarines were each armed with two 450 mm torpedoes in muzzle - loading tubes one above the other on the port bow . In the Pearl Harbor attack , the specially designed Type 97 torpedo was used , but problems with the oxygen flasks meant that all later attacks used a different torpedo . Some have stated that a version of the Type 91 torpedo , designed for aircraft launching , was used , but other reports indicate that the Type 97 torpedo was modified to the Type 98 , otherwise known as the Type 97 special . There is no definitive information that the Type 91 was used . The Type 98 was later supplanted by the Type 02 torpedo . There was also a demolition charge which it has been suggested was large enough to enable the submarine to be used as a suicide weapon , but there is no evidence that it was ever used as one . Each submarine had a crew of two men . A junior officer conned the boat while a petty officer manipulated valves and moved ballast to control trim and diving . Pearl Harbor attack . Five of these boats participated in the Pearl Harbor attack , with two actually making it into the harbor . Of the five used at Pearl Harbor , " No . 19 " was captured with its pilot Kazuo Sakamaki where it grounded on the east side of Oahu . During World War II , " No . 19 " was put on tour across the United States to help sell War Bonds . Now a U . S . National Historic Landmark , " No . 19 " is an exhibit at the National Museum of the Pacific War in Fredericksburg , Texas . A second Pearl Harbor midget submarine , " No . 18 " , was located by U . S . Navy divers off Keehi Lagoon east of the Pearl Harbor entrance on 13 June 1960 . The submarine had been damaged by a depth charge attack and abandoned by its crew before it could fire its torpedoes . This submarine was restored and placed on display at the Imperial Japanese Naval Academy on 15 March 1962 . The midget submarine attacked by at 6 : 37 a . m . on 7 December , " No . 20 " , was located in 400 meters ( 1 , 312 feet ) of water five miles outside Pearl Harbor by a University of Hawaii research submersible on 28 August 2002 . A fourth submarine , " No . 22 " , entered the harbor and fired its torpedoes at and . Both of those torpedoes missed and are believed to have hit a dock at Pearl City and the shore of Ford Island . This submarine was sunk by " Monaghan " at 8 : 43 a . m . on 7 December and later recovered and used as fill during construction of a new landside pier at the Pearl Harbor submarine base . The hulk was uncovered again in 1952 but was so badly corroded by chlorine gas from the electrical batteries that it was again reburied at the same location . The crew ' s remains are still entombed in the submarine . In 2009 , a research team assembled by PBS " Nova " positively identified the remains of a midget sub found outside the Pearl Harbor entrance as being the last of the 5 Ko - Hyoteki that participated in the December 7 , 1941 , attack . It was discovered in salvage from the wreckage of the West Loch Disaster of 1944 , dumped three miles south of Pearl Harbor . Secret war records show that submarine crews had been ordered to scuttle their subs after the attack and provisions were made to recover stranded crews . It is believed the fifth sub successfully entered Pearl , fired on Battleship Row , and escaped to the relative quiet of neighbouring West Loch , where it was scuttled by the crew . When a series of explosions sank an amphibious fleet being assembled in the Loch in 1944 , the remains of the sub were collected and dumped in the subsequent salvage operation , which was kept classified as secret until 1960 . The torpedo tubes in the bow section were empty , indicating that the fifth midget had fired its torpedoes prior to being scuttled . A photograph taken from a Japanese plane during the Pearl Harbor attack appears to show a midget submarine inside the harbor firing torpedoes at Battleship Row . This new evidence suggests that the capsizing of the may have been accelerated by a torpedo hit from a submarine - launched torpedo , the warhead of which was roughly twice the power of that carried by the air - dropped torpedoes . In the photo , where the torpedoes ' paths had supposedly started , were sprays that indicated a midget - submarine rocking up and down due to the force of the torpedo being launched , causing the propellers of the stern to be exposed , kicking up clouds of water spray . A war time report from Admiral Nimitz confirmed the recovery of dud torpedoes of the type employed by the midget submarines . This discovery is covered in PBS " Nova " television program " Killer Subs in Pearl Harbor " and companion website , I - 16tou . com . Japanese midget submarine attacks on Sydney . On the night of 29 May 1942 , five large Japanese submarines positioned themselves 56 kilometres north - east of Sydney Heads . At 3 a . m . the next day one of the submarines launched a reconnaissance aircraft . After circling Sydney Harbour the aircraft returned to its submarine , reporting the presence of ' battleships and cruisers ' moored in the harbour . The flotilla ' s commanding officer decided to attack the harbour with midget submarines the next night . The next day the five submarines approached to within 11 kilometres of Sydney Heads , and at about 4 : 30 p . m . they released three midget submarines , which then began their approach to Sydney Harbour . The outer - harbour defences detected the entry of the first midget submarine , " No . 14 " , at about 8 p . m . , but it was not identified until it became entangled in an anti - torpedo net that was suspended between George ' s Head and Green Point . Before HMAS " Yarroma " was able to open fire , the submarine ' s two crew members destroyed their vessel with demolition charges and killed themselves . The second submarine , " No . 24b " , entered the harbour at about 9 . 48 p . m . and headed west towards the Sydney Harbour Bridge , causing a general alarm to be issued by the Naval Officer in Charge , Sydney . About 200 metres from Garden Island the submarine was fired on by the heavy cruiser . The submarine then fired its two torpedoes at the cruiser . One torpedo ran ashore on Garden Island , but failed to explode . The other passed under the Dutch submarine " K9 " and struck the harbour bed beneath the depot ship HMAS " Kuttabul " where it exploded , killing 21 sailors ( 19 Royal Australian Navy and 2 Royal Navy ) . The submarine then slipped out of the harbour , its mission complete , and disappeared . Its wreck was located , about 30 km north of the harbour and 5 km to seaward , in November 2006 . It is now protected as a war grave . The third submarine , " No . 21 " , was sighted by HMAS " Yandra " at the entrance to the harbour and was depth - charged . Some four hours later , having recovered , it entered the harbour , but it was subsequently attacked with depth charge s and sunk in Taylor Bay by vessels of the Royal Australian Navy . Both members of the submarine ' s crew committed suicide . The two submarines that were recovered were identical , and their remains were used to reconstruct a complete submarine , which toured New South Wales , Victoria and South Australia before being delivered to the Australian War Memorial in Canberra in 1943 , where it remains on display . Japanese midget submarine attacks on Madagascar . On the 29 May 1942 , the Japanese submarine s " I - 10 " , " I - 16 " and " I - 20 " arrived on Madagascar . " I - 10 " s reconnaissance plane spotted " Revenge " - class battleship at anchor in Diego Suarez harbor but the plane was spotted and " Ramillies " changed her berth . " I - 20 " and " I - 16 " launched two midget submarines , one of which managed to enter the harbor and fired two torpedoes while under depth charge attack from two corvette s . One torpedo seriously damaged " Ramillies " , while the second sank the 6 , 993 ton oil tanker " British Loyalty " ( later refloated ) . " Ramillies " was later repaired in Durban and Plymouth . The crew of one of the submarines , Lieutenant Saburo Akieda and Petty Officer Masami Takemoto , beached their submarine ( " No . 20b " ) at Nosy Antalikely and moved inland towards their pick - up point near Cape Amber . They were informed upon when they bought food at a village and both were killed in a firefight with Royal Marines three days later . The second midget submarine , " No . 16b " , was lost at sea and the body of one of its crew was found washed ashore a day later .