Aikoku Maru

The Aikoku Maru was one of the war's hybrid ships: a fast, handsome OSK liner completed in 1940, armed and sent raiding in the Indian Ocean early in the war, later reduced to hauling troops and munitions as Japan's perimeter contracted. On 17 February 1944 she lay at Truk loaded with both. A dive bomber's hit reached her forward holds, and the resulting explosion was among the most violent of the raid — it obliterated the front third of the ship and, by many accounts, caught the attacking aircraft in the blast. She sank at once, taking hundreds of soldiers and sailors with her; no reliable count survives. What remains sits upright and deep: an amputated ship beginning abruptly amidships, superstructure looming out of dim water past forty meters. Survivor associations have placed memorials aboard, and of all Chuuk's wrecks she carries the strongest claim to be left in peace. Technical divers visit; everyone else should read about her instead.

How she sank: A bomb detonated her forward munitions cargo during Operation Hailstone, 17 February 1944.

Condition: The surviving aft two-thirds is intact and imposing; the bow area is unrecognizable blast wreckage.

Penetration: Limited. Interior work at these depths is for experienced technical teams; most visits stay outside the superstructure, and the memorial spaces are not thoroughfares. Entering any overhead environment requires specific training — a wreck certification at minimum, technical wreck training for full penetration.

Recommended certification: Technical/trimix certification

Current: Mild · Visibility: 15–30 m

Marine life: Black corals and hydroids at depth, big groupers under the counter, and trevally hunting along the broken forward edge.

Hazards: Depth and decompression obligation govern everything; unexploded ordnance is scattered through the wreckage; light is low.

Chuuk lagoon monument protection; state dive permit/fee applies.

Among the most heavily weighted war graves in the lagoon — hundreds died here in a single moment. Memorial plaques aboard mark it; treat the entire wreck as consecrated ground.

Nothing is removed from this ship, ever.