Smith Rock is a cluster of granite pinnacles between Cape Moreton and Flinders Reef that has claimed at least three ships, and today it is one of the most rewarding reef dives off the northern end of Moreton Island. The pinnacles rise from about 21 m to within 6 m of the surface and are split by gutters, swim-throughs and small caverns, giving divers plenty of structure to explore in a single dive. Scattered ship debris from the wrecks that struck the rock lies among the boulders.

Because the rock is exposed to swell and to the strong tidal stream that sweeps past the cape, it is less often visited than Flinders Reef, and the payoff is abundant fish. Crayfish are common in the cracks, and the regional guides mention large marine species, shovelnose rays and sharks, along with schools of reef and pelagic fish that gather in the current. Colourful sponge and coral growth covers the granite.

Nigel Marsh describes it as a colourful reef with caves and canyons, dropping to about 30 m on the surrounding sand. The rock's history adds to the dive. The iron barque Aarhus struck it in 1894 and sank within minutes; the French steamer St Paul hit it in 1914 and went down in deep water a kilometre to the east; and the freighter Marietta Dal ran aground on it in 1950, scattering tractors and machinery.

All three wrecks are dived from the same area, and many divers combine Smith Rock with one of them. Visibility of 20-30 m is common in winter. The site suits advanced divers who are comfortable timing a dive around slack water and handling current if the timing slips.

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.

Smith Rock sits in the tidal stream that runs past Cape Moreton, and swell and strong currents are common. Operators say it should be dived at slack water; plan the dive for the turn of the tide and expect the current to pick up quickly afterwards. Swell over about 1.5 m from the east or south-east produces surge and breaking water over the shallow pinnacles, and strong southerlies make the cape rough.

Visibility averages 15 m in summer and 20-30 m in winter, which is also the calmer season.

Time the entry for slack water. Descend on the pinnacles at 8-12 m, explore the swim-throughs and caverns between the granite blocks while working down to 18-21 m, and look for scattered ship debris. Turn with the current in mind and ascend on a DSMB if the boat is live-boating.

Brisbane Scuba and Go Dive Brisbane (Manly) – on outer-Moreton days when the current allows; Supercat Charters – charter; Brisbane Sub-Aqua Club – club trips combining Flinders, Smith Rock and Cementco.