Diving the wreck of the IJN oiler IRO at Palau

The15, 450-ton IJN oiler IRO arrived at Palau for repair in late March 1944, after being torpedoed in the bow by the American submarine USS Tunny.

On 30 March 1944, the 2-day US Task Force 58 fast carrier strike, code named Operation DESECRATE 1, began against Japanese shipping and aircraft at Palau. IRO was hit by a 1,000-lb bomb from USS Bunker Hill planes - but remained afloat.

The following day, 31 March 1944, the air attacks resumed - and she was hit starboard aft by a US bomb with a delayed fuze. The bomb punched through her shell plating before exploding in her engine room and starting fierce fires. She settled by the stern, her stern grounding on the seabed - her bow rearing high into the air to expose the damage to her stem by the USS Tunny torpedo.

The buoyancy of her empty forward oil tanks kept her afloat for some three weeks before she finally disappeared under the surface.

The wreck of the IRO today rests upright in just over 40 metres of water.