Type 97 torpedo

The Type 97 was a 17.7 inches (45 cm) diameter torpedo used by the Imperial Japanese Navy during World War II.

Intended for use with Japan's Kō-hyōteki-class midget submarines, the torpedo was based on the 24-inch diameter Type 93 "Long Lance" used by Japanese surface vessels, but redesigned to meet the smaller 18-inch physical dimensions of the midgets' two torpedo tubes.

Four Type 97 Special torpedoes were fired during the Japanese midget submarine raid on Sydney Harbour in the early hours of June 1, 1942.

Two were fired by the midget M-24 and aimed at the American heavy cruiser USS Chicago, then tied to the No 2. buoy at Garden Island in Sydney Harbour.

One struck the harbour wall beneath the depot ship HMAS Kuttabul, sinking the converted ferry and killing 19 Australian and 2 British sailors aboard.