A24-1 was the first Catalina taken on charge by the RAAF, a PBY-5 flying boat with a long wartime history. Darwin Harbour was a major flying-boat base during the Second World War. US Navy Patrol Wing 10 PBYs were moored in the harbour when the Japanese attacked on 19 February 1942, and from 1944 the RAAF operated Catalina squadrons from the harbour on long-range minelaying and patrol missions into the Netherlands East Indies. At least three RAAF and six US Navy Catalinas were lost in the harbour, and DSAC numbers the known wrecks Catalina 1 to 6. The PBY Catalina had a 31.7 m wingspan, a 19.4 m hull and an empty weight of about 9,500 kg, so even a broken wreck covers a surprising area of seabed. On 30 August 1945, piloted by Wing Commander Keith Bolitho, A24-1 crashed during take-off in the harbour. The wreck was towed onto a mud bank in East Arm for salvage and left there.

Today it is the shallowest and most degraded of the harbour's Catalinas, lying at the mangrove edge in no more than about 5 m at high tide. Decades of tidal scouring have broken the airframe down to the nose section, fragments of the wings and the two engines, which are exposed at low tide. Parts were recovered for the restoration of a Catalina displayed at RAAF Base Amberley, and DSAC holds photographs of the aircraft on the mud bank in the late 1960s. It is less a scenic dive than a historical inspection in thick water, and it is only accessible around high water. The mangrove setting brings a much higher crocodile risk than the open-harbour sites, which is why few divers go. It is of most interest to aviation historians and to divers completing DSAC's list of harbour Catalinas; for most visitors the engines visible from a boat at low tide tell the story well enough.

Boat only. The Catalina wrecks lie in the East Arm of Darwin Harbour, south-east of the city past the port. The closest launch is the East Arm public boat ramp near the East Arm port; from Cullen Bay or the Stokes Hill / Frances Bay ramp allow about 20-30 minutes around Stokes Hill and down the harbour.

Positions are held by DSAC and the NT Heritage Branch rather than published, so dive with someone who has the mark, drop a shot clear of the wreck and time the dive for neap high-water slack. East Arm is more sheltered from the trade winds than the outer harbour but the water is often murkier. A24-1 lies on an intertidal mud bank against the mangroves, so the approach is only possible near high tide.

Tide is everything in Darwin Harbour: the spring range is 7-8 m and tidal streams run hard through the harbour, so diving is generally only possible on neap tides (range under about 3-4 m), timed to the slack at high water when clearer ocean water sits over the site. Spring tides bring strong currents and silt-laden water with near-zero visibility. The dry season (May-October) gives the most consistent conditions; the south-east trade winds can chop up exposed water in the afternoon, so mornings are best.

In the wet season (November-April) run-off from the rivers and creeks drops visibility, afternoon storms build quickly, and the harbour is in cyclone season; box jellyfish are present October-May.

Only at high tide on a neap. Anchor off in deeper water, swim in along the bottom to the nose section, look at the wing fragments and the two engines, and leave before the tide begins to drop. Stay together and keep the boat close for a quick exit.

No regular commercial trips; dived by Darwin Sub Aqua Club members and occasional private groups with the mark on neap-tide days.