The Great Barrier Reef: Earth's Largest Living Structure, Off Queensland

The **Great Barrier Reef** lies in the **Coral Sea, off the coast of Queensland, Australia**, stretching **2,300 km (1,430 mi)** from the Torres Strait (north) to near Bundaberg (south).

Scale & Structure

• Area: 344,400 km² (133,000 sq mi) — larger than Italy, ~size of Germany/Japan.
• Components: ~2,900 individual reefs + 900 islands (cays & continental).
• Depth: Mostly shallow (<30m) on reef flats; outer slopes drop to 2,000m.

Biodiversity Hotspot

• 1,500+ fish species (clownfish, grouper, parrotfish).
• 400+ hard/soft coral species (build the reef).
• 4,000+ mollusks (giant clams, cones).
• 6 of 7 marine turtle species; dugongs; 30+ whale/dolphin species; seabirds.

Status & Threats

• UNESCO World Heritage (1981).
• Major Threats: Climate change (mass bleaching 2016, 2017, 2020, 2022), crown-of-thorns starfish outbreaks, agricultural runoff (sediment/nutrients), coastal development, cyclones.
• Management: Great Barrier Reef Marine Park Authority (zoning: no-take, general use).

It is the only living structure visible from space.