About how long is the Great Barrier Reef, in kilometers?

The Great Barrier Reef is about 2,300 kilometers long. It stretches along the northeastern coast of Queensland, Australia, in the Coral Sea, making it the world’s largest coral reef system.

Despite being called a single reef, it is a vast network made up of more than 2,900 individual reefs and about 900 islands. Its living structure is built by billions of tiny coral polyps, which secrete calcium-carbonate skeletons that accumulate over many generations.

The reef lies offshore rather than forming a continuous wall directly beside the mainland. In places, a broad channel separates it from the coast. The Great Barrier Reef is also often confused with the world’s largest single organism or a single uninterrupted reef; more precisely, it is an interconnected system of reefs, islands, shoals and lagoons.