I-34 was a Kaidai Junsen Type B1 submarine of the Imperial Japanese Navy. During World War II, while on a Yanagi mission between Japan and Germany carrying strategic raw materials and information, she was sunk by the British submarine using Ultra intelligence.
Her keel was laid down at the Sasebo Dockyard on 1 January 1941; she was launched on 24 September. She was commissioned and assigned to the Kure Naval District on 31 August 1942, with Commander Tonozuka Kinzo in command. Commander Tatsushi Irie (入江達) took command in March 1943.
During early 1943, she took part in supply missions and the eventual evacuation of the garrison of Kiska in the Aleutian Islands.
On 15 September 1943, she was assigned to a Yanagi (exchange) mission to Lorient, France. She arrived in Singapore on 22 October 1943 to take on passengers and cargo for her mission.
I-34 loaded a cargo of raw rubber, tungsten, tin, quinine, medicinal opium and samples of Japanese weapons. She departed for Penang to load passengers on 11 November 1943. Due to a delay in loading the cargo, her passengers opted to meet her at Penang, thus saving them from death.
Unknown to Commander Irie or the crew, her movements were being tracked by Ultra intelligence, and a British submarine was sent to sink her.
She was spotted running on the surface in a rain squall by HMS Taurus (commanded by veteran Captain Mervyn R. G. "Dillinger" Wingfield, DSO, DSC), on 13 November 1943 in the Malacca Straits, 30nmi off the coast of Penang at 07:30.
Taurus fired a salvo of six torpedoes of which one struck I-34 below the conning tower, she sank in 100feet of water at 5.2833°N 105°W. Of her 94 crew, only 14 survived to be picked up by a local junk.
I-34 was removed from the Imperial Japanese Navy list in January 1944. Her wreck was salvaged in 1962.