Diving the Aikoku Maru

The Aikoku Maru had an interesting military career, as she was a sub tender and merchant raider during the war. A merchant raider, or XCL, is a civilian ship which is converted into a kind of light warship. An XCL is essentially a pirate ship, raiding enemy shipping while disguised as a commercial vessel.

The Aikoku was armed with eight inch naval guns, torpedo tubes and antiaircraft weapons. She even carried a floatplane to scout for targets and direct fire for the artillery. The floatplane was mounted on a catapult aft of the superstructure and landed in the water. Recovering the plane was accomplished with one of the cargo hoists.

Two of the missions that the Aikoku carried out were particularly interesting. During one raid into the Indian Ocean, she was steaming in convoy with her sister ship, the Hokoku Maru. The ships had intended to sink or capture an enemy tanker which was being escorted by a little minesweeper. The minesweeper, the Bengal, bravely stood off the two XCLs with its single 6" deck gun against the sixteen 8" guns of the Japanese ships. When the smoke had cleared the Aikoku was running for port at flank speed, the Hokoku was on the bottom, and the Bengal was escorting the damaged Genoa back to port.

The second mission involved the capture of a New Zealand ship called the MV Hauraki. The Hauraki was sent back to Japan and entered the Emperor's service as a transport, serving the Japanese in the South Seas. The Hauraki was renamed the Hoki Maru and sunk in Truk, only a mile away from the Aikoku.

The last voyage of the Aikoku was an effort to bring troops and ordinance to the Micronesian islands. The 1st Amphibious Brigade was transferred from mainland Asia, and intended to reinforce the garrisons in the Marshall Islands, east of Truk. By the time the Aikoku was approaching the fighting, however, the US had taken the most important bases in the area. The Aikoku turned back to Truk, just a day ahead of the attacking US Task Force 58. At dawn on February 17th, planes from the Intrepid found the Aikoku riding her anchor in the Combined Fleet Anchorage.

The troops aboard the Aikoku had probably hoped to go ashore to get out of the makeshift billets they were crammed into aboard the Aikoku, but there were no barracks built for them. During the attack ordinance in the forward holds exploded, sending the ship to the bottom along with the attacking plane and its crew, most of the ships hands and 750 of men of the First Brigade.

Diving the Aikoku is a great experience. The ship has a massive superstructure with eight decks abaft the funnel. The explosion that sunk the Aikoku sheared off the fore ship. Nothing remains of ship from the bridge forward, but the superstructure and aft ship are quite interesting. The antiaircraft guns are still pointing skyward, just as they were back in 1944. Heaps of spent cartridges lie next to the guns. 

It has been said that the engine room and aft holds are great dives with lots to see, but at this depth it's a very technical dive to attempt any penetration. The structure has also been weakened by a half-century of rust and the explosion which destroyed the fore ship. Some of the decks are already collapsing, so the interior of the Aikoku may be considered as high risk to penetrate.

She went down on the Windward side of Dublon.


A diver swims past one of the big antiaircraft guns. The angle of the gun indicates that the Aikoku went down fighting.

 Photo by Peter Ording

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