The Althea 2 is a steel fishing trawler that sank in 1991 and now sits alone on sand in 41 m of water, roughly halfway between Bundaberg and the northern tip of K'gari. It is the deepest and most remote wreck in the Bundaberg list, and for that reason one of the least dived.

Marinelife.org.au reports that the hull and superstructure are still intact – unusual for a small wreck after three decades – and that the wreck's isolation on bare sand makes it an oasis for big fish. Giant trevally, barracuda, Spanish mackerel, kingfish and queenfish hunt over it; leopard sharks, wobbegongs and stingrays rest on and beside it; moray eels and lionfish live in the structure. On a good day, with 10 m or more visibility, the wreck is surrounded by fish from the sand to the top of the wheelhouse.

Depth is the defining factor. With the sand at 41 m and the top of the wreck in the mid-30s, bottom time on air is very short and narcosis is significant. This is a dive for experienced deep divers with appropriate gas planning – ideally technical divers using trimix or at least a conservative nitrox and decompression plan – and it needs a capable boat, a long weather window and someone topside.

There is no regular operator and little published information beyond the marinelife.org.au summary and GPS mark. It is included here for completeness: for most divers the ex-HMAS Tobruk, which lies in the same stretch of water at 11-28 m and is serviced by several operators, is the practical big-wreck dive in this area.

Launch at Burnett Heads boat ramp (15 km north-east of Bundaberg) and run north-east across open water to the mark published by marinelife.org.au (24°33'57''S 152°49'45''E), roughly 50 km from the ramp – allow 60-90 minutes in a trailer boat in good conditions. This is a long offshore run: take a capable vessel, EPIRB and a boat handler who stays aboard. Drop a shot on the wreck; there is no mooring.

The Althea lies in exposed water off the northern end of K'gari and needs flat conditions – winds under about 10-12 knots and seas under 1 m – for the long run from Burnett Heads. South-east trades above 15 knots rule it out. Marinelife.org.au recommends July-August on a high tide, when visibility (typically around 10 m) and current are most favourable; dive at high-water slack.

Summer storms and plankton reduce visibility.

Descend the shot directly to the wreck at 33-41 m and plan a short no-deco or planned-deco dive around the hull and superstructure, staying on the upcurrent side. Turn early, ascend the shot line and complete staged stops. Use nitrox or trimix as appropriate and carry an SMB in case you lose the line.

Depth 33-41 m. Air diving is marginal; trimix or conservative nitrox with planned decompression recommended. Carry redundant gas and an SMB; boat cover required.

No regular operator – private boat or technical/club charter only; Bundaberg Aqua Scuba may advise.