Montevideo Maru was a Japanese auxiliary ship during World War II. It was sunk by the American submarine USS Sturgeon on 1 July 1942, drowning 1,054 Australians aboard – prisoners of war and civilians who were being transported from Rabaul to Hainan. The sinking is considered the worst maritime disaster in Australia's history. The wreck of the Montevideo Maru was discovered in 2023.