IJN Submarine I-1

The big Japanese cruiser submarine I-1 lies on the outside of the reef off Tambea which is a small village about 25 miles (40 km) west of Honiara. The submarine was 320 feet long with an endurance of 60 days and a range of 24,000 miles. The I-1 ran aground on the reef in January 1943 after a battle with two New Zealand corvettes. The submarine now lies with the shattered bow in 15 feet (5 m) and the stern in 100 feet (30 m) of water.

During a cruise in the Solomons in September 2004 on the MV Princess II, we anchored off Tambea while two crewmembers went ashore to pay the custom fee for diving on the wreck. Meanwhile we geared up on the dive deck and made a plan to dive down to the stern of the I-1 and then move slowly up the wreck to the shallow reef area.

We could see the long ‘cigar tube’ shape of the aft section of the submarine and swam down the outside to the stern. The propellers were salvaged in the 1960s and the rudder is buried in the sand. We swam along the rear deck and I entered the first area where the hull is fractured. There is a great deal of machinery inside and several large air cylinders. I swam through a small circular frame which must have once been a watertight door.

Back on the outside, the conning tower is nowhere to be seen and the ship itself is severely damaged. The forward half of the submarine is blown wide open with debris all over the reef.  Apparently the salvagers blew up the bow section which set off some live torpedoes in the torpedo room!  We finished the dive on the shallow reef where we admired the colourful anemonefish.

According to Jane’s Fighting Ships of World War II, the I-1 was 320 feet (97.5 metres) long and had a displacement of 1955/2480 tons. I-1 was the first of the Junsen class of Japanese ocean-going submarines and was completed in 1926. The submarine was originally armed with two 140-mm (5.5-inch) deck guns and had six 21-inch torpedo tubes. Although it was a big submarine, larger I-class submarines were built before and during WWII. According to I-1’s Tabular Record of Movement, it was converted to a cargo-carrying role in August 1942 by removing the aft 140-mm (5.5-inch) gun to make room for mountings to hold a 46-foot landing barge.

On 29 January 1943, the I-1 arrived off the coast with a crew of 82, replacement troops, and a load of food supplies in rubber containers in the barge on the rear deck. The submarine was detected by the New Zealand corvettes HMNZS Kiwi and HMNZS Moa which dropped depth charges forcing it to surface, exchanged gunfire and rammed it three times. During the battle, the barge of supplies caught fire and the captain was hit by gunfire. The damaged submarine finally ran onto the reef off Tambea.

Since the submarine carried code books, the Japanese armed forces tried to destroy it on several occasions, but failed to prevent the recovery of the books by the US Navy. However, the submarine (particularly the bow section) was severely damaged by salvage operations in search of valuable metals in the 1960s.

A full account of the fate of the I-1 can be found in the Tabular Record of Movement at the Combined Fleet website.

Reference: Jane’s Fighting Ships of World War II.