On 17 February 1944 the Rio de Janeiro Maru was anchored east of Uman Island (Chuuk). On February 17th 1944, during operation Hailstone, TF-58 planes from aircraft carriers bomb the Rio de Janeiro Maru, off Truk. She sinks on 18th, just after midnight.
Ocean Liner, built in 1930 by Mitsubishi Zosen Kaisha for the Osaka Shosen Kaisha (OSK) Line. In 1940, she was requisitioned by the Japanese government and used as a submarine tender.
The dive
Rio de Janeiro Maru lies at a maximum depth of about 34 metres on its starboard side. As you swim down onto the wreck it is quickly obvious that this is a huge wreck, the fourth biggest in Chuuk Lagoon in terms of tonnage.
I scanned the wreck on Feb. 25th 2025 during one dive.
