The largest structure on Earth built by living organisms, around 344,400 square kilometres
Some 2,900 reefs and 900 islands off the Queensland coast
Geography · Physical geography
The Great Barrier Reef
Australia — off the Queensland coast, in the Coral Sea
The world's largest coral reef system: some 2,900 individual reefs and 900 islands strung along about 2,300 kilometres of the Queensland coast and covering roughly 344,400 square kilometres. It is the largest structure on Earth built by living organisms, and since 1998 it has suffered a run of mass bleaching events as sea temperatures have climbed.
How to spot them
- ▸The largest structure on Earth made by living things
- ▸Quiz clue: 'crown-of-thorns starfish', 'bleaching', 'zooxanthellae', 'Whitsundays', 'Coral Sea'
- ▸Inscribed by UNESCO in 1981 and run by a marine park authority created in 1975
- ▸Cook's Endeavour was holed on it in 1770
Key facts
It stretches roughly 2,300 kilometres, from the Torres Strait almost to Bundaberg
Up to about 250 km wide in places
HMS Endeavour struck it in June 1770 and was beached for repairs at the mouth of a Queensland river (1770)
The river and the town that grew there are both named Cooktown after the episode
The coral-eating crown-of-thorns starfish periodically erupts across it in devastating outbreaks
Acanthaster planci, controlled by divers injecting individual starfish
Mass bleaching struck it in 1998, 2002, 2016, 2017, 2020, 2022 and 2024
Heat stress makes the coral expel its symbiotic algae, exposing the white skeleton beneath
Once a year, on a night after a spring full moon, its corals spawn all at once
Synchronised mass spawning, described by Australian researchers in the early 1980s
An Australian statutory authority has managed it as a marine park since 1975 (1975)
Created after a campaign against oil drilling and limestone mining
Quick-fire facts
- •It covers about 344,400 km² and comprises roughly 2,900 reefs and 900 islands
- •It runs some 2,300 km along the Queensland coast and is up to 250 km wide
- •It was inscribed as a UNESCO World Heritage site in 1981
- •It supports around 1,500 fish species, 400 coral species, six of the world's seven marine turtle species and the dugong
- •Bleaching is not death: bleached coral has expelled its zooxanthellae and can recover if the heat stress passes
- •The Great Barrier Reef Marine Park Authority was established in 1975
- •The world's second-largest barrier reef is the Mesoamerican Barrier Reef, off Belize
- •Common misconception: it is not one reef but thousands, and it is not visible from the Moon — only from low Earth orbit
Drill it — 8 cards
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Sources
- UNESCO World Heritage Centre — Great Barrier Reef
- Zvy Dubinsky and Noga Stambler (eds) — Coral Reefs: An Ecosystem in Transition