Montevideo Maru () was a merchant ship of the Empire of Japan. Launched in 1926, it was pressed into service as a military transport during World War II. It was sunk by the American submarine on 1 July 1942, drowning 1,054 people, mostly Australian prisoners of war and civilians who were being transported from Rabaul, the former Australian territory of New Guinea, to Hainan. The sinking is considered the worst maritime disaster in Australia's history. The wreck of the Montevideo Maru was discovered on 18 April 2023.
