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 Montevideo Maru was discovered on 18 April 2023.
Pre-war history
Montevideo Maru was one of three ships (along with Santos Maru and La Plata Maru) of the Osaka Shosen Kaisha (OSK) shipping line built for their trans-Pacific service to South America. The ship was constructed at the Mitsubishi Zosen Kakoki Kaisha shipyard at Nagasaki, and launched in 1926.
World War II service
Montevideo Maru participated in the invasion of Makassar, Celebes, from 6 to 16 February, 1942. It completed several transport missions before being sunk. The ship was proceeding without escort to the Chinese island of Hainan, when it was sighted by the American submarine near the northern Philippine coast on 30 June 1942. Montevideo Maru slowed to about at midnight, to facilitate an expected rendezvous with an escort of two destroyers.