Australia's Great Barrier Reef stretches more than 2,300 kilometres along the Queensland coastline, making it the largest living structure on Earth. Visible from space, this extraordinary ecosystem is not a single reef but a mosaic of nearly 3,000 individual reefs and 900 islands, all interwoven like a vast underwater tapestry. The reef supports an astonishing diversity of life. More than 1,500 species of fish, 4,000 types of mollusc and six of the world's seven marine turtle species depend on this habitat. Coral polyps — tiny animals no larger than a fingernail — are the architects of this entire world. Each polyp secretes a hard calcium carbonate skeleton, and over thousands of years these skeletal remains accumulate into the towering reef structures we see today. Despite its grandeur, the Great Barrier Reef is under serious pressure. Rising ocean temperatures, caused by climate change, trigger a phenomenon known as coral bleaching. When water becomes too warm, corals expel the microscopic algae living within their tissues. Without these algae, which provide corals with up to 90 per cent of their energy through photosynthesis, the coral turns ghostly white and may eventually die. Mass bleaching events have struck the reef repeatedly in recent decades, alarming marine scientists worldwide. Water quality poses an additional threat. Agricultural runoff carrying fertilisers and sediment from Queensland's coastal farms clouds the water, reducing the sunlight that corals and algae need to survive. Crown-of-thorns starfish, which feed on coral, also multiply rapidly in nutrient-rich water, further stripping the reef of its colour and complexity. Conservation efforts are ongoing. The Australian Government, researchers and Traditional Owners — who have cared for these waters for tens of thousands of years — are working collaboratively to monitor, restore and protect this irreplaceable natural wonder before its vibrant colours fade permanently beneath the warming sea.