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(Yamada)
RIO DE JANEIRO MARU 
UNDERWATER
IMAGES
The Rio de Janeiro Maru was built in 1931 by the Mitsubishi Zosensho Company of Nagasaki as a passenger ship for the Osaka Soshen Kaisha Line. Her peacetime duties consisted of passenger and cargo carriage on around the world route from Japan via Hong Kong, Singapore, South Africa, South America, US west coast and finally back to Yokahama, Japan.
The Japanese Navy took control of her in 1940 and converted her to a submarine tender. She was attached to the Combined Fleet and was responsible for servicing and supply of six submarines. After 1943, the Japanese had lost most of their submarines, so Rio de Janeiro Maru was reclassified a transport and based in Truk.
During the "Hailstone" attack, Rio de Janeiro Maru was attacked by aircraft from the carrier USS Essex and hit with at least one bomb. She was reported on fire and thought to have sunk on the first day. She now lies in 130 fsw.
Rio de Janeiro Maru: Displacement: 9,627 tons; Length: 450 feet; Beam: 62 feet; Engines: 2-Mitsubishi Sulzer diesel; Max Speed: 17.6 kts. Armament: 2- 6 inch dual purpose guns; anti-aircraft machine guns. Launched: circa 1925. Crew:150.
Courtesy-Capt. Lance Higgs S.S. Thorfinn