Coral Gardens is a gently sloping reef on the Wistari Channel side of Heron Reef, adjacent to the island's research station, and it is exactly what its name promises: the entire site is covered in hard and soft corals of many types and shapes. The resort lists it in its top ten and recommends it to divers who simply like coral. Staghorn groves, plate corals, massive corals and soft coral colonies cover the slope, and crustaceans live among the branches, where scorpionfish lie camouflaged waiting for prey.

Yellow-striped sea perch school over the reef, and the channel location means turtles, reef sharks and occasionally manta rays pass along the slope. The site is usually dived in the afternoon as a shallow dive, and when the tide is running along Wistari Channel it can be done as a gentle drift, covering a longer stretch of reef. Near slack water it is a relaxed, stationary reef dive with plenty of time to look for small creatures.

Coral Gardens suits all certification levels and is good for photographers who want coral-scape images in bright light. It gives a sense of the extent and variety of healthy coral on Heron Reef, which is protected as a Marine National Park (Green) Zone. Divers should note that Lady Elliot Island also has a well-known site called Coral Gardens; the two are unrelated.

Because the site lies so close to the research station, it is also one of the most studied patches of reef in the southern Great Barrier Reef, and divers may see marker stakes or survey equipment, which should be left undisturbed. A torch helps reveal the scorpionfish and crustaceans tucked into the coral branches.

Heron Island is 72 km north-east of Gladstone. Fly or drive to Gladstone, then take the Heron Islander ferry from the Gladstone Marina terminal (72 Bryan Jordan Drive; check-in from 7:45 am, departs 9:30 am on scheduled days, about 2 hours), or transfer by seaplane or helicopter. Dive gear is carried on the ferry in addition to baggage.

On the island, the dive centre sits beside the harbour; boats leave the jetty for three dives daily and most Heron Reef sites are 5-15 minutes away. Coral Gardens lies on the Wistari Channel side of Heron Reef near the research station, about 5 minutes from the jetty.

Heron Reef sites are chosen on the day by wind and tide. The prevailing south-east trade winds (strongest April-September, often 15-25 knots) make the southern and south-eastern reef edge rough, so the sheltered northern and western sites are dived most. Northerly winds in spring and summer reverse this.

The tidal range is up to 3-4 m and currents run strongly around the reef edge and through Wistari Channel on springs; visibility is usually best on the incoming tide. Cyclone season is November-April; summer storms and plankton blooms can drop visibility to 10 m. Stingers are uncommon this far south but present in summer.

Coral Gardens faces Wistari Channel, so tidal flow along the channel is the main factor; it is dived as a drift when the current runs and as a relaxed reef dive near slack.

Descend onto the upper slope at 6-8 m and follow the coral down to 12-15 m, drifting with any current along the channel wall. Work back up the slope through the staghorn groves and finish in the shallows for the safety stop, with the boat collecting you if drifting.

Heron Island Resort Dive Centre is the only operator: three guided boat dives a day (about 9 am, 11 am and 3 pm) plus scheduled night dives, from the resort jetty; sites are rotated by tide and wind. Access requires a stay at Heron Island Resort (or the University of Queensland research station). Usually scheduled as a shallow afternoon dive.