Great Barrier Reef

The Great Barrier Reef is the planet's largest coral reef ecosystem, covering roughly 344,400 square kilometers in the Coral Sea off northeastern Australia. It includes about 3,000 individual reefs, 600 continental islands, 300 coral cays, and mangrove-fringed estuaries. Warm, clear tropical waters and the south-flowing East Australian Current nurture more than 600 hard and soft coral species. Seagrass meadows shelter dugongs and green sea turtles, while outer reefs host reef sharks, manta rays, and vibrant reef fish such as parrotfish and butterflyfish.

The reef began forming around 20,000 years ago when rising sea levels flooded the continental shelf after the last Ice Age. Tiny coral polyps built limestone skeletons, creating underwater mountains that continue to grow up toward sunlight. The system buffers Queensland's coastline from storms and supports fisheries, tourism, and cultural traditions of Aboriginal and Torres Strait Islander peoples. Some reefs, such as Ribbon Reefs near Cooktown, remain relatively pristine, while other sections experience coral bleaching caused by marine heatwaves.

Climate change is the reef's greatest threat. Hotter ocean temperatures lead to mass bleaching events when stressed corals expel symbiotic algae. Without relief, corals can die, reducing habitat for fish and crustaceans. Ocean acidification makes it harder for corals and shellfish to build skeletons. In addition, pollution from agricultural runoff fuels algal blooms, and outbreaks of crown-of-thorns starfish consume corals faster than they can recover. Scientists, government agencies, and Traditional Owners collaborate on monitoring, reef restoration, and water-quality improvements.

Management falls under the Great Barrier Reef Marine Park Authority (GBRMPA), which zones the Marine Park for fishing, tourism, conservation, and shipping. Sustainable tourism operators follow best practices such as installing moorings to avoid anchor damage, limiting visitor numbers, and educating guests about reef etiquette. Indigenous ranger groups conduct sea-country patrols, remove ghost nets, and record cultural sites. Research stations on Heron, Lizard, and Orpheus Islands host marine biologists studying coral resilience, genetics, and potential heat-resistant coral strains.

Visitors can experience the reef through snorkeling, scuba diving, glass-bottom boats, and scenic flights. Whitsunday Islands offer white-sand beaches and sailing adventures, while Lady Elliot Island provides opportunities to swim with manta rays. Reef HQ Aquarium in Townsville, currently undergoing upgrades, brings coral education to mainland audiences. Teachers use citizen-science apps such as Eye on the Reef to submit fish counts and coral-health snapshots, helping scientists track conditions across the reef's enormous area.