Japanese submarine Ro-34, Submarine wreck in the Solomon Islands

The Japanese submarine Ro-34 was a medium-sized cruiser submarine of the Imperial Japanese Navy.

Ro-34 was laid down at Mitsubishi's Kobe shipyard on 25 April 1934, launched on 12 December 1935, and commissioned on 31 May 1937. She took part in the 1940 Imperial Naval Review at Yokohama and was sunk on 5 April 1943 by the U.S. destroyer O'Bannon near the Russell Islands, with all 66 crew lost.

Ro-34's name derives from the Ro designation for medium submarines; the boat was laid down at Mitsubishi's Kobe yard on 25 April 1934 and launched on 12 December 1935. A memorial stele (chūkonhi) to her crew stands in a military cemetery in Iyo, Ehime Prefecture. In August 1939 she carried a nutritionist from Tokyo Imperial University on a research cruise to Saipan studying crew diet and confinement.

The wreck lies in the Russell Islands area of the Solomon Islands, at roughly 8.25°S 158.97°E, sunk on 5 April 1943 by the U.S. destroyer O'Bannon during the I-Go operation. No marked grave or memorial marks the site; a memorial stele for the crew stands in a military cemetery in Iyo, Ehime Prefecture, Japan.

Ro-34 was sunk on 5 April 1943 near the Russell Islands by the U.S. destroyer USS O'Bannon; all 66 crew members, including commander Tomita Rikichi, were killed. The wreck lies in the Solomon Sea, not in Japan.