Ro-33 was a Ro-33-class submarine of the Imperial Japanese Navy. Commissioned on October 7, 1935 the submarine saw action for Imperial Japanese forces during the Pacific Campaign of World War II. On 7 August 1942, Ro-33 sank the Australian motor vessel Mamutu in the Gulf of Papua near Murray Island, Torres Strait, with the loss of 114 lives. After shelling Mamutu until she was sinking, Ro-33's commander, Shigeshi Kuriyama, then ordered his gunners to open fire on the survivors, men women and children, as they struggled in the water. Of the full complement of passengers and crew, there were only 28 survivors. The submarine was sunk near Port Moresby, Papua New Guinea with all hands (70 officers and men) by the Royal Australian Navy destroyer Arunta at 09°36′S 147°06′E / 9.600°S 147.100°E on August 29, 1942.
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- Hackett, Bob; Sander Kingsepp (2003). "HIJMS Submarine RO-33: Tabular Record of Movement". Sensuikan!. Combinedfleet.com. Retrieved 10 May 2009.
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