Famous for its diving, Heron Island is small enough to walk around in an hour, with half the cay occupied by a comfortable resort and research station, and the rest covered in groves of pandanus, coconuts and shady pisonias. You can literally walk off the beach and into the Reef’s maze of coral, or swim along the shallow walls looking for action. The eastern edges of the lagoon are good for snorkelling at any time, although some of the best coral is on the outer reefs, accessible only by boat. A drift along the wall facing Wistari reef to Heron Bommie covers about everything you’re likely to encounter. The coral isn’t that good but the amount of life is astonishing: tiny boxfish hide under ledges; turtles, cowries, wobbegong, reef sharks, moray eels, butterfly cod and octopuses secrete themselves among the coral; manta rays soar majestically; and larger reef fish gape vacantly as you drift past. The bommie itself makes first-rate snorkelling, with an interesting swim-through if your lungs are up to it, while the Tenements along the reef ’s northern edge are good for bigger game – including sharks.

All this natural wonder is the exclusive preserve of well-heeled ecotourists – the island is not open for day-trips or camping. Access to the island is by ferry or helicopter from Gladstone.