Qualla: Japanese submarine Ro-33

Japanese submarine Ro-33: Introduction

Thu, 09 Apr 2026 00:00:00 GMT

Seventy men went down with her. At 13:05 on 29 August 1942, the Royal Australian Navy destroyer HMAS Arunta began dropping depth charges on a sonar contact ten nautical miles southeast of Port Moresby. By the fourth attack, a large oil slick had risen to the surface. Beneath it lay the Imperial Japanese Navy submarine Ro-33 and her entire crew, lost in the dark water of the Gulf of Papua during her fifth war patrol. She had been the lead boat of her class, commissioned less than seven years earlier. She had torpedoed the merchant ship Malaita just hours before. Her war ended in minutes, somewhere below the Coral Sea.

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Japanese submarine Ro-33: Built at Kure

Thu, 09 Apr 2026 00:00:00 GMT

Ro-33 was laid down on 8 August 1933 at the Kure Naval Arsenal in Japan, launched on 10 October 1934, and commissioned in November 1935. She was the lead submarine of her class - the K5 sub-class of the Kaichu type, a refinement of the preceding KT boats with greater surface spee...

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Japanese submarine Ro-33: A War Across the Ocean

Thu, 09 Apr 2026 00:00:00 GMT

Ro-33 served in the South China Sea, the Indian Ocean, and the southwestern Pacific. She operated in support of the Japanese invasion of British Malaya in December 1941, the invasion of Java in early 1942, the Battle of the Coral Sea in May 1942, and the opening moves of the Guad...

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Japanese submarine Ro-33: The Fifth Patrol

Thu, 09 Apr 2026 00:00:00 GMT

Six days later, on 22 August 1942, Ro-33 sailed from Rabaul on what turned out to be her final patrol. Her assignment: a patrol area off Port Moresby, supporting the Japanese push across the Owen Stanley Range in the New Guinea campaign. By 25 August she was off southeastern New ...

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Japanese submarine Ro-33: The Torpedoing of Malaita

Thu, 09 Apr 2026 00:00:00 GMT

On 29 August, the 3,310-ton merchant ship Malaita left Port Moresby bound for Cairns, Australia, escorted by HMAS Arunta. The escort was there because Japanese aircraft had been raiding the Gulf of Papua. Nobody was expecting a submarine. At sometime before 12:45, west of Port Mo...

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Japanese submarine Ro-33: An Oil Slick, Seventy Lives

Thu, 09 Apr 2026 00:00:00 GMT

Arunta's sonar found Ro-33 ten nautical miles southeast of Port Moresby. Four depth-charge attacks, starting at 13:05, produced the oil slick that told the Australian crew what they'd done. Depth-charge warfare was brutal and impersonal - a destroyer dropping canisters set to exp...

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