Search
The search for the Japanese midget sub has been ongoing for 61 years since it was first sunk. In its latest phase, the Hawaii Undersea Research Lab has conducted towed side scan sonar surveys of the debris fields off Pearl Harbor. At the end of World War II, obsolete war material was dumped in 1,000-3,000 feet of water several miles off Pearl Harbor. This included: landing craft, tanks, old aircraft, trucks, barges, small ships, fuel tanks etc. There are on the order of 1,000 significant sonar targets in the area. Sorting through these various targets to identify the most promising ones to dive on as a submersible pilot training exercise has been the work of many years. The Japanese midget submarine although giving a very clear return on the side scan survey was interspersed with other debris on the bottom complicating the search efforts.
Findings
The Japanese midget submarine was found in 400 m of water about five miles off the mouth of Pearl Harbor. As it is an historically significant military vessel and (per agreement with the government of Japan) a property of the U.S. federal government, its exact location is being protected by the U.S. State Department and heritage resource management agencies. The submarine sits upright on the bottom and is in amazingly good condition as shown in the photos. Both torpedoes are still in place. The submarine has no apparent depth charge damage but does have shell damage on both sides of the conning tower. The port side of the conning tower exhibits what one analyst has identified as shrapnel holes. This would presumably have come from the first shell fired by the USS Ward which exploded near the submarine but did not directly hit it. The starboard side of the conning tower shows a hole from the 4 inch shell fired by the side gun on the Ward as the ship steamed past. Apparently, this shell did not explode on impact as the midget sub conning tower is clearly still in place. While four depth charges were dropped directly on the midget as the Ward passed by, the charges were set to go off at a depth of 100 feet and the submarine was at the surface. The pressure wave created by the 4 depth charges was sufficient to fully lift the 46 ton, 78 foot midget out of the water, but did no visually apparent structural damage. The midget sub sank from flooding through the four inch shell hole.
