Submarines of the Imperial Japanese Navy
In 1904 Kawasaki Dockyard Company purchased plans for a modified version directly from Holland, and built two boats (Hulls No. 6 and 7), with the help of two American engineers, Chase and Herbert, who had been assistants to Holland. The Kawasaki-type submarines displaced 63 and 95 tons when submerged, and measured in overall length, respectively. both vessels measured at the beam. This contrasted with the original five imported Hollands-type submarines which had arrived that same year, at over 100 tons submerged, in overall length and beam. The Kawasaki Type #6 and #7 submarines had gained extra speed and reduced fuel consumption by . However both boats could launch only one torpedo, and each was manned by 14 sailors, whereas the imported Holland-type submarines could fire two torpedoes and could be operated by 13 sailors. This new type was designated the Type 6 submarine by the Imperial Japanese Navy, and was used primarily for test purposes.
Scuttling
To prevent a Soviet inspection team from examining surrendered Imperial Japanese Navy submarines after World War II, the United States Navy conducted Operation Road's End, in which it scuttled 24 of the submarines in the East China Sea off Fukue Island on 1 April 1946. Nine more Japanese submarines followed on 5 April, and another six went down by early May. In addition, U.S. Navy submarines sank four surrendered Japanese submarines as targets in the Pacific Ocean near Hawaii in May and June 1946, and the Royal Australian Navy sank six or seven (sources differ) surrendered Japanese submarines in the Seto Inland Sea on 8 May 1946 in Operation Bottom.