Great Barrier Reef Site Features

Scale

Stretching more than 2,000 kilometers along Australia's northeastern coast, the Great Barrier Reef covers roughly 348,000 square kilometers -- an area comparable in size to Italy -- making it the largest living structure on the planet and, per NASA photography from orbit, one of the few visible from space. It's made up of around 3,000 individual reefs and hundreds of islands and coral cays, together accounting for roughly a tenth of the world's coral reef ecosystems.

Marine life

The reef supports an extraordinary range of marine life: more than 1,500 species of fish, around 400 species of coral, six of the world's seven species of marine turtle, and thousands of species of mollusks, crustaceans, sponges, and other invertebrates. Dugongs, reef sharks, and migrating humpback whales also pass through its waters at different times of year.

Diving and island access

Most visitors experience the reef by boat, with dive and snorkel operators running trips out from towns along the Queensland coast such as Cairns and Port Douglas, or from islands like Green Island and the Whitsundays that sit within the reef system itself. Popular sites range from shallow coral gardens suited to snorkelers to deeper dive sites like the Cod Hole and the SS Yongala wreck, where visibility and marine life vary considerably by location and season.

The reef runs along the edge of Australia's continental shelf in the Coral Sea, separated from the Queensland coast by a lagoon that varies from a few kilometers wide in the north to more than 200 kilometers wide near its southern end.

Its nearly 3,000 individual reefs and around 900 islands range from small sand cays to larger continental islands like those in the Whitsundays, giving the system a genuinely varied landscape rather than one continuous formation.

The reef's northern sections, closer to the equator, tend to have healthier coral cover than areas further south, where warmer water temperatures and agricultural runoff from the mainland have caused more visible coral bleaching and decline in recent decades.