The wreckage of one of the submarines sunk at Pearl Harbor was located by NOAA's Hawaii Undersea Research Laboratory (HURL) in August 2002.[29] Photographic analysis conducted by the United States Naval Institute in 1999 indicated that one of the five Ko-hyoteki-class submarines managed to enter Pearl Harbor, and successfully fired a torpedo into USS West Virginia. On 29 May 1942, one of two midget submarines managed to enter the Diego Suarez harbor and fire two torpedoes. One torpedo seriously damaged the battleship HMS Ramillies, while the second sank the oil tanker British Loyalty (6,993 tons).