The Rufus King was an American Liberty ship, one of the mass-produced cargo vessels of the Second World War. On 7 July 1942, inbound to Brisbane from Los Angeles with military equipment including nine Mitchell bombers, aviation fuel and medical supplies, she ran aground on the Amity Bar in South Passage, between Moreton and North Stradbroke islands, and broke in two. The forward section was refloated and later used as a lighter, but the stern remained on the bar, where it is still visible at low water and remains a hazard to navigation. marinelife.org.au notes that the wreck is regularly visited by spearfishers and makes a shallow dive in good weather.

The broken steel provides structure in an otherwise sandy, high-energy environment, so it concentrates fish: expect schools of baitfish, trevally, mulloway, bream and snapper around the hull, with rays and wobbegongs on the sand and the occasional turtle. The appeal is historical as much as biological – this is a tangible reminder of Brisbane's role as a major Allied base in the Pacific war. The difficulty is the location.

South Passage has a fearsome reputation among boaters, with breaking swell, shifting sandbanks and strong tidal flows, and the wreck can only be dived in rare calm conditions at slack water. It is therefore not suitable for inexperienced divers or boat handlers. Those who do dive it should keep a person on the boat, fly a dive flag and plan to leave before the tide turns.

Check the latest bar conditions with Coast Guard before heading out.

Boat access only. Launch at Amity Point on North Stradbroke Island (reach Straddie by SeaLink ferry from Cleveland to Dunwich, then drive about 20 minutes north to Amity) and run a short distance out towards the South Passage Bar. The bar is shallow, shifting and dangerous in swell – only approach in calm conditions with local knowledge.

The stern is visible at low water and is a navigation hazard.

The South Passage Bar is one of the most dangerous bars in South East Queensland: breaking waves, shifting sandbanks and strong tidal currents. Dive only in very calm conditions with little or no easterly swell, at slack water – marinelife.org.au suggests about one and a half hours before the Brisbane Bar high tide. Visibility is best on the flood and poor on the ebb.

Anchor clear of the wreck on a calm day at slack water, descend and circle the stern section, then return well before the tide turns. Keep a boat cover person on board.

No commercial operator; regularly visited by spearfishers and occasionally by experienced private divers in calm weather.