Junsen Type J1
During the short battle, the submarine altered course to starboard just before HMNZS Kiwi rammed it on the port side abaft of the conning tower. Numerous hits were landed at this time. HMNZS Kiwi again rammed the submarine and an officer, was seen to be hit by machine-gun fire. A third ramming damaged both vessels and HMNZS Moa took up the chase, following the submarine while continually firing its gun. More than two hours after the first attack, the I-1 hit the reef near Kamimbo Bay. The next morning, the wreck was projecting 40' to 50' out of the water at an angle of 45 degrees.
In reports, the sinking of the I-1 was claimed by USS Gamble DD-123. It would appear that somehow the submarines have been mixed up and what was meant in the Gamble's reports was that it sank the I-123.
During the late 1960s or early 1970s, Australian Wally Gibbons blew up the bow section of the submarine in search of booty. Although this caused a great deal of damage (there was still one or two live torpedoes inside), the bow sections of the sub are still on-site, but opened up. The front one-third is basically destroyed with the remaining section still virtually intact.
Ewan Stevenson adds:
On the sand adjacent to the vessel's port side near the 15 meter level is a huge battery compartment with hundreds of wet-cell batteries in and around it. Other interesting objects to be seen include air-bank cylinders (used for discharging ballast tanks) and the huge electric motors that powered the vessel underwater. It is a simple matter to follow the debris to the main part of the wreck. At about the 18 meter level you can enter the submarine and penetrate right through to the stern. At the stern you can see the submarine's dive planes, rudder and propeller shafts. The return dive can be done on the outside. This is an excellent dive and like most of the wrecks around Honiara, the coral and fish life in the shallower sections are very good.