Coral Gardens is the mooring most often used to introduce divers to Flynn Reef, and it earns the name. The reef top is a broad garden of staghorn thickets, table and plate corals and boulder colonies in 3-8 m of water, lit by strong sunlight and crowded with small reef fish. At the edge of the garden the reef steps off into a wall that falls to around 30 m, with swim-throughs and overhangs cut into it at 12-20 m.

That combination makes it one of the better all-round sites in the Cairns southern reefs: new divers can stay in the shallows and still see a great deal, while more experienced divers can spend the first part of the dive on the wall before coming up to finish in the garden. The wall face carries sea fans and soft corals, and the overhangs hold soldierfish, sweepers and the occasional sleeping whitetip reef shark. Out in the blue there are big-eye trevally, schools of chevron barracuda and fusiliers, and reef sharks cruise the base of the wall.

Manta, devil and eagle rays pass through from time to time, more often in winter. In the garden look for clownfish in their anemones, batfish hanging near the mooring, coral trout and cod under the plates, and butterflyfish, angelfish and anthias over the coral heads. Giant clams are scattered across the reef flat.

Flynn is one of the reefs Pro Dive Cairns uses for liveaboard night dives, and Coral Gardens is a good one: the wall comes alive with feeding crustaceans, sleeping parrotfish and hunting reef sharks. It suits every level from recently certified divers to photographers who want a wall and a garden in one tank.

Boat access only. Cairns day boats leave from the Reef Fleet Terminal (1 Spence Street) and the neighbouring Marlin Marina on the city waterfront, with check-in between about 7:00 and 8:00 am; most operators run transfers from city and northern-beaches accommodation, and there is paid parking near the terminal. The run of about 57 km out through Trinity Inlet and across the lagoon to Flynn Reef takes around 80 minutes on a fast catamaran and noticeably longer on slower dive boats or into a south-easterly chop.

Flynn is visited by Silverswift and Passions of Paradise day boats and on the Pro Dive Cairns liveaboard; the skipper chooses between the Flynn moorings on the day according to wind, so Coral Gardens cannot be guaranteed. Divers kit up on the boat during the run out and enter from the stern platform directly onto the mooring.

The prevailing south-east trade winds (typically 15-25 knots from April to September) are what limit Cairns outer-reef diving: above about 25 knots trips may be cancelled, and exposed eastern moorings are used only in light winds. Summer northerlies are gentler but make north-facing moorings choppy. Box jellyfish and Irukandji are present from about November to May (stinger suits on every dive), and the cyclone season runs November to April, when a system in the Coral Sea can close the reef for days.

Visibility drops after heavy rain and strong winds; spring is usually calmest and clearest. Coral Gardens sits on the sheltered side of Flynn and is one of the moorings used in a moderate south-easterly. Best at slack or on a flooding tide, when the wall has the clearest water; it is a regular night-dive mooring for liveaboards.

Descend the mooring to the sand at about 12 m, turn to put the reef on your shoulder and follow the wall down to 18-25 m for the first third of the dive, looking into the overhangs and swim-throughs. Turn at a third of your gas, come up onto the garden at 8-10 m and zig-zag back across the staghorn and table corals toward the boat, finishing with a safety stop over the reef top at 5 m.

Silverswift (Silverseries) – daily day trips, three dives, rotating between Flynn, Milln, Thetford and Pellowe; Passions of Paradise – daily sailing-catamaran day trips to Flynn moorings; Pro Dive Cairns – 3-day/2-night liveaboard, sites on Flynn, Milln, Thetford and Pellowe including night dives