Flinders Reef is Brisbane's signature dive: a small coral reef sitting in open ocean just north of Cape Moreton that holds more coral species than any other subtropical reef on Australia's east coast. Charter operators like to say it has more varieties of coral in one small area than any single reef on the Great Barrier Reef, and with more than 100 hard and soft coral species and over 175 recorded fish species it genuinely looks like a piece of the tropics transplanted to South East Queensland. It has been a marine park since 1998 and is now a Marine National Park (green) zone, so nothing may be taken and the fish show it.

The reef is compact, rising from about 20-28 m of sand to a few rocky heads that break the surface at low tide. The western side is the sheltered, shallow side, with coral gardens at 5-12 m of plate, staghorn and brain corals, soft corals, gorgonians and sponges, cut by sand gutters. The eastern side is more rugged, with walls, ledges, small caves and pinnacles dropping to the mid-twenties.

Much of the dive is spent in 6-16 m, which makes Flinders suitable for new divers and good for long, relaxed dives. The big draw is the turtle cleaning station on the western side, where green and loggerhead turtles queue over a bommie to be picked clean by surgeonfish and cleaner wrasse; divers who stay low and still get close-range views. Around the reef you will see schools of sweetlip, trevally, batfish, surgeonfish, parrotfish and wrasse, plenty of wobbegongs tucked under ledges, eagle rays passing over the sand, leopard sharks and manta rays in summer, and occasional grey nurse sharks and whaler sharks on the eastern side.

In winter humpback whales migrate past and are often heard, and sometimes seen, during the dive. Look closely for nudibranchs, egg cowries, feather duster worms and anemonefish. Flinders is usually combined with the Cementco wreck or Gotham City on a two-dive day, and it is the natural first outer-Moreton trip for divers who have done the bay sites.

Because the crossing is long, it rewards picking a settled day.

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. Flinders Reef has several public moorings; anchoring on the reef is not permitted.

Flinders sits in open ocean north of Cape Moreton, so the limiting factor is the crossing and the swell. Northerly and north-easterly winds over about 15 knots and any easterly or north-easterly swell over 1.5 m make the moorings rough and the shallow tops surgy; strong southerlies make the run around the cape unpleasant. The best days follow a period of light westerly or south-westerly winds, typical of winter mornings.

The reef is not strongly tidal, but a light current can run across the eastern side. Visibility averages 15 m in summer and 30 m in winter, and drops after big easterly swells or when the Brisbane River plume is pushed north after heavy rain.

Pick up a public mooring on the western side, descend the line to 8-10 m and swim a loose circuit of the coral gardens and gutters, keeping the reef on one shoulder. Visit the turtle cleaning station in about 5 m near the end of the dive, then return to the mooring and do the safety stop on the line. Second dives often move to a mooring on the eastern side for the ledges, caves and a chance of larger pelagics.

Brisbane Scuba (Manly) – regular Moreton Island day trips pairing Flinders with Cementco or Gotham City; Go Dive Brisbane and Brisbane Dive Academy – scheduled Flinders days; Sunreef and Scuba World (Mooloolaba) – regular Flinders Reef double-dive trips (about 7 hours door to door); Supercat Charters – charter trips.