People snorkelling on Outer Great Barrier Reef near Cairns, North Queensland, Australia, Pacific

People snorkelling on Outer Great Barrier Reef near Cairns, North Queensland, Australia, Pacific

Swarm of fish Blackfin barracudas (Sphyraena qenie), swimming in blue water, Great Barrier Reef, Unesco World Heritage, Coral Sea, Pacific Ocean, Australia, Oceania

Oceanic whitetip shark (Carcharhinus longimanus) from front, back light, Great Barrier Reef, Unesco World Heritage, Coral Sea, Pacific, Australia, Oceania

Reef manta ray (Mobula alfredi) swim with open head fins in blue water, Great Barrier Reef, Unesco World Heritage, Coral Sea, Pacific Ocean, Australia, Oceania

Diver observes reef manta ray (Mobula alfredi), Great Barrier Reef, Unesco World Heritage, Coral Sea, Pacific, Australia, Oceania

Swarm of fish Bigeye trevallies (Caranx sexfasciatus) swims over coral reef, Great Barrier Reef, Unesco World Heritage, Coral Sea, Pacific, Australia, Oceania

Humphead wrasse (Cheilinus undulatus) over coral reef, the Great Barrier Reef, Pacific, Australia, Oceania

Fringing reef around small island with runway, Lady Elliot Island, Queensland, Pacific, Australia, Oceania

Seaplane in Great Barrier Reef Marine Park, Whitsunday Islands National Park, Whitsunday Islands, Queensland, Australia, Oceania

Aerial view, Heart Reef, Great Barrier Reef, UNESCO World Heritage Site, Queensland, Australia, Oceania

Red Lionfish (Pterois volitans) swims over coral reef in the backlight of the sun, Great Barrier Reef, Unesco World Heritage, Pacific, Australia, Oceania

Striped Surgeonfish (Acanthurus lineatus), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Swarm Spotted eagle ray (Aetobatus narinari), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Green humphead parrotfish (Bolbometopon muricatum) sleeps at night in shelter, Great Barrier Reef, Unesco World Heritage, Pacific, Australia, Oceania

Clown triggerfish (Balistoides conspicillum), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Aerial view of the Whitsunday Islands, Queensland, Australia, Oceania

Golden damselfish (Amblyglyphidodon aureus) in front of red rod gorgonian (Ellisella ceratophyta), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Royal angelfish (Pygoplites diacanthus), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Threadfin anthias (Pseudanthias huchtii) Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Aerial view of the Great Barrier Reef, UNESCO World Heritage Site, Queensland, Australia, Oceania

Striped threefin (Helcogramma striata), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Flagtail Rockcod (Cephalopholis urodeta), Great Barrier Reef, Unesco World Heritage Site, Pacific, Australia, Oceania

Aerial view of the Great Barrier Reef, UNESCO World Heritage Site, Queensland, Australia, Oceania