The I-169 Submarine was a 337ft/102m, 1,400 ton Cruiser-Submarine launched on February 15th, 1934, and one of a class of six known as Kaidai Type 6A that had been developed from large British submarine technology.
Originally known as ‘I-69’, her class of submarine was built under the 1931 Fleet First Replenishment Law by the Mitsubishi Zosensho shipyard in Kobe, Japan. It was much faster than prior Japanese submarines with a surface speed of 23.9 knots, a submerged speed of 8.8 knots (electric) and a safe diving depth of 230ft/70m. However, the submarines of this class did little to distinguish themselves during World War II with the exception of the I-168 that sank the carrier USS Yorktown and the destroyer USS Hamman at the Battle of Midway. None of the submarines of this class survived the war.
In December of 1941 the I-169 was assigned to the 6th Submarine Fleet based in Kwajalein in the Marshall Islands. She and 8 other submarines were stationed south of Oahu Island as part of a post-strike blockade in support of the aircraft carrier attack on Pearl Harbor. Over 30 Japanese submarines participated in this operation, including 5 fleet submarines that off-loaded midget submarines to penetrate the boom protecting the harbor entrance. The I-169 was forced to submerge while under attack by U.S. destroyers and became fouled in anti-submarine cables. After trying in vain to become unentangled, and with the crew about to suffocate after 38 hours underwater with no opportunity to surface, the crew ate a ‘last meal’ before destroying all of its secret documents. Following one last desperate attempt to break free by powering full speed astern, the I-169 broke free. Thereafter, she provided replenishment support services at Midway and the Kurile and Aleutian Islands.
On April 2nd 1944 while in Truk between patrols, a second air raid took place, and the I-169 was forced to submerge for protection since there were no submarine pens built at Truk Lagoon. Afterward it failed to resurface, and a rescue diver discovered that the upper valve of the storm ventilation tube in the aft part of the conning tower was open a couple of inches. In response to hammering on the hull, the diver received responses from four of five hatches. When attempts to raise the sub failed, with the exception of the captain, Shigeo Shinoharu, who was not aboard at the time, the entire crew of 9 officers and 75 men suffocated to death. Fearing capture of the hull after an anticipated invasion of Allied forces, the Japanese depth charged the forward part of the sub and conning tower, but left the aft part untouched. The I-169 rests on the sea bottom at 144ft/43m.