The Aarhus was a 640-tonne, 170 ft iron sailing barque built in Hamburg in 1875. She left New York for Brisbane on 24 February 1894 carrying kerosene and general merchandise, and at the end of the long voyage she struck Smith Rock off Cape Moreton not once but three times before sinking within about 12 minutes. More than a century later she lies at 18-25 m on sand beside the rock that sank her.

Much of the wreck is covered by sand, but sections remain exposed and recognisable. The starboard bow section stands above the seabed, and around it divers can find the bowsprit, anchors, deck plating and bales of wire from the cargo. Sand movement changes how much is visible from year to year.

The wreck is now a living reef: sponges and corals encrust the iron, schools of bigeyes shelter in the shadows of the plating, and pelagic schools swirl above. Rays, octopus and wobbegongs are regularly seen, and the proximity to Smith Rock means larger fish move between the reef and the wreck. Visibility is often 20-30 m, which lets divers take in the scattered remains in context.

The Aarhus lies in a protected zone and a permit is required to dive it, so trips are run through operators who hold one; nothing may be touched or removed. The strong currents that sweep the area are the main challenge, and slack-water timing is essential. For divers interested in maritime history it is the oldest of the three Smith Rock wrecks and an evocative reminder of how dangerous the approach to Moreton Bay was in the days of sail.

Boat access only. Brisbane charters leave from Manly Boat Harbour (Brisbane Scuba departs from the corner of Royal Esplanade and Davenport Drive, Manly) or from Scarborough Boat Harbour on the Redcliffe Peninsula, crossing Moreton Bay and running out through the North West Channel past Bulwer and Comboyuro Point to the northern tip of Moreton Island. Allow roughly 75-90 minutes from Manly in good conditions.

Sunshine Coast operators run south from The Wharf, Mooloolaba, in about 45 minutes. Private boats typically launch at Scarborough or Bribie Island; the open-water crossing around Cape Moreton is exposed and should only be attempted in settled weather with local knowledge. Smith Rock lies between Cape Moreton and Flinders Reef, a short run from the cape; the three historic wrecks lie on and around it.

Diving within the protected zone around the wreck requires a permit, which operators hold.

Currents of up to 2 knots run past Smith Rock, so the Aarhus must be dived at slack water. Plan around the turn of the tide and be ready to abort if the current is running. Swell over 1.5 m from the east or south-east causes surge on the site; strong southerlies make the cape crossing rough.

Visibility averages 20-30 m, especially in winter.

Descend at slack water onto the starboard bow section, which stands above the seabed, then follow the scattered plating, anchors and wire bales across the sand. Keep track of time at 20-25 m and return towards the rock or ascend on a DSMB.

Protected historic shipwreck – permit held by operators. Nitrox useful at 20-25 m.

Supercat Charters and Brisbane operators (Brisbane Scuba, Go Dive Brisbane) – occasional trips on outer-Moreton days at slack water; permit held by operator.