Irako

The deck arrives at twenty-eight metres and the sand is another fifteen below it. That gap is the planning problem in one number, and it is the reason this dive starts on a clock. Most of the exterior work happens on and just above the deck: the bow, a gun platform with no gun left on it, and a thick mast with crosstrees and a crow's nest covered in huge barrel sponges. Bigeye trevally are the constant. They pour down both sides of the hull and turn in a slow column around the mast.

The interior is a separate dive and it is what she is known for. The published route enters at the wheelhouse, past the ship's wheel, into a hold, and from there the ship opens out into corridors and gangways with doorways, machinery and ladders running off in all directions. The galley still holds its huge rice cauldrons. The machine shop has pillar drills and wiring hanging everywhere. Deep inside, a bicycle leans against a cabin wall, and a heavy wheel that once lifted ammunition to the gun platform is still in place.

What it costs is the rest of the story. The routes inside her are smaller and darker than on the other Coron wrecks, they run six or more rooms deep, and they reach points where there is no light at all beyond what you brought. Bomb damage compressed parts of some decks to about a metre and a half of headroom1. Silt lifts easily. Perfect buoyancy is not a compliment here, it is the entry requirement, and the engine-room route through the ship is technical diving, not a longer version of the same dive.

Coming back out onto the deck is the moment divers describe afterwards. The light returns, the jacks are still there filling the blue above the hull, and the ascent runs up the mast to the crow's nest and its sponges. Then the safety stop, and often a decompression stop before it.

Local divemasters call her the three Ds: deep, dark and dangerous. The nickname earns its keep, because on every other wreck in Coron the interior is a bonus and here it is the dive. The swim-throughs elsewhere in the bay are wide and lit. Hers are neither, and that is precisely why wreck divers rank her first.

The fittings are why they come back a second and a third time. Rice cauldrons and sinks in a galley built to feed a fleet, drills in the machine shop, catwalks, a bicycle nobody has moved in eighty years. Divers who dived the whole Coron fleet name her as the wreck with the most left in her for someone with the training to look, and they also say she takes several dives to learn. That is a booking decision as much as a diving one.

She reads differently from her neighbours for a simple reason. The Okikawa Maru is the long shallow tanker with encrusted decks in the light and the longest bottom times in the bay. The Akitsushima has the guns and the seaplane crane out on the sand. The Irako has depth and an interior, and divers choose between those three the way they choose a favourite.

She was laid down at Kawasaki's yard in Kobe on 30 May 1940 as transport No. 74, named Irako on 5 February 1941, launched nine days after that and completed on 5 December 19412. She was a provision store ship, built for the job rather than converted to it, with refrigerated holds and food-preparation shops below decks so that a fleet at anchor could be supplied without going home. Her tall funnel came from boilers that could burn coal as well as oil.

The name matters more than it looks. She was a commissioned navy vessel, not a merchant ship, so the suffix maru that shop lists attach to her is wrong2. At about 147 metres by 19 she was a large ship by the standards of what else went down here1.

On 23 September 1944 she anchored between Tangat and Lusong, part of a supply fleet that had left Manila Bay believing Coron sat beyond the reach of American carriers. It did not. The next morning aircraft of the US Third Fleet flew some 340 miles to the anchorage and attacked shortly before nine. Direct bomb hits landed amidships, her bridge and superstructure caught fire, and she began to sink by the bow and was beached. Later she slipped off and sank at the mouth of the bay2. The bridge is still the one part of her that is not largely intact, which matches the record of where she was hit.

Gas planning is the first decision, not the last one. The local practice on this wreck is to pick the nitrox mix by deck level: roughly 32 percent for bottom time at deck level, something leaner for interior work deeper in the ship. Not every shop in town stocks nitrox, so raise it when you book, not on the boat.

Carry a torch and a second one. Inside her there are rooms with no natural light at all, and a single light failure at 35 metres in a corridor is a different problem from a light failure on a reef.

Settle what you are going into before you get in the water. Operators here vary materially in what they will let a customer do, and divers have described being offered an interior on the boat and finding themselves in the dark with no sense of the way out. Agree the route and the limits on the surface, and be willing to decline an entry underwater even after you agreed to it. If the visibility is bad on the day, the honest answer is to dive her outside.

Stay off the structure. Scorpionfish sit on the ledges and lionfish hover through the frames, the metal is folded and sharp where the bombs landed, and nothing on this ship is yours. She passed the fifty-year mark in 1994, which makes everything on and in the hull state-owned cultural property under Republic Act No. 10066, and disturbing the site at all takes written authority and museum supervision3. Take photographs.

Then the part that is easy to leave until too late. No working recompression chamber is confirmed in Coron, and this is the deepest wreck in the bay that gets dived every week. The nearest chamber reported working is in Puerto Princesa, which is in the same province and still awkward, because no airline flies Busuanga to Puerto Princesa direct and the scheduled route goes through Manila. Hold insurance that pays for hyperbaric treatment and for the evacuation flight, check the boat carries oxygen, and ask your operator where the chamber question stands on the day you dive.