Irako

The Irako, a roughly 147 m Imperial Japanese Navy refrigerated provision ship, went down in the air strikes of 24 September 1944 and settled almost upright, largely intact, which is why many rate it the finest wreck in the Philippines. It is also the deepest of Coron's regular fleet: decks around 28-34 m, seabed past 40. Trained wreck divers work the galley spaces and the cathedral-dark engine room, where machinery stands in place under a fur of silt; everyone else patrols the rails among lionfish, grouper, and schooling snapper. Lives were lost when she sank, and guides brief the fleet's wartime dead accordingly.

The moment you come for: Coron's most intact major wreck, famed engine-room penetration for the trained, big fish on a big hull

Topography: Upright hull on a mud-sand seabed at 42-45 m

Current: Usually calm at depth; descents run down a mooring line.

Hazards: Depth, dark silty interiors, sharp steel, and short no-deco windows; penetration requires training, lights, and a guide who knows the hull.

Conservation: A historic wartime loss: artifacts stay aboard, and operators expect respectful conduct throughout the fleet.

Nitrox: Worth it here — profiles sit in the range where enriched air meaningfully extends no-stop time (with the training to use it).