IJN
Sentoku Type
I-400 Class Submarine
1945
University of Hawaii 2005
Length
400'
Tons
3,530 (surfaced)
5,223 (submerged)
Armament
8 x torpedo tubes
5.5" deck gun
bridge 25mm AA gun
3 x 3x25mm AA gun
Hanger
3 x Seiran Float
Planes
Crew
21 officers
174 enlisted men
Captain Ariizumi
Ship History
Construction began on September 29, 1943 at Kobe under heavy security.
Wartime History
It was planned to use the I-400 along with the I-401, I-13 and I-14 to participate in a daring plan to attack the Panama Canal and disable its locks. In June 1945 the decision was made to switch targets to hit USN anchorage at Ulithi Atoll. The plan was code-named Arashi (storm) for the I-400 and I-401 to use its Serians on Kamikaze attacks on any carriers based there. The two subs departed Ominato on July 23, 1945.
The sub was fired upon by friendly shore batteries at the Tsugaru Strait, but suffered no damage. After passing through a storm, the sub spotted aircraft and screw noise near Marcus Island, forcing them to detour to the east, and sent a message to I-400 to rendezvous 100 miles south of Ponape, but the other sub failed to receive it. The strike date was set for August 17th, but Japan surrendered on the 15th.
Surrender
After hearing of the surrender, the Captain elected to return to Yokosuka, to surrender in Japanese home waters. They jettisoned their Serain aircraft. USS Segundo SS-398 located her on radar and negotiated for the sub's surrender. On the voyage back, the captain Ariizumi committed suicide, and the sub was surrendered by its LtCdr Nambu. Sailed to Hawaii, and evaluated
by the US Navy.
Sinking History
Sunk on May 31, 1946 at 10:59am by two
torpedoes from the USS Cabezon (SS-334), testing the Mark 10-3 exploder in deep water. Over the course of several days four captured subs were sunk: I-201, I-14, and I-400.
Discovery
On March 17, 2005, a University of Hawaii's Hawaii Undersea Research Laboratory's (HURL) submersible discovered the submarine lying flat on the sea floor at 2665'. It was identified from the I-401 painted on the side of the coning tower. The submersible recorded video and stills of the wreck.
Relics
Some items were taken by USN prior to its sinking and survive today. The Yokohama WWII Japanese Military Radio Museum has one of the sub's gun sites on display.
820m 2,665'
21 12 N
158 07 W
Tabular Movements
HURL Discovery
