Name the largest coral reef system in the world.

The Great Barrier Reef is recognized as the largest coral reef system in the world, extending over 2,300 kilometers along the coast of Queensland, Australia. This extensive ecosystem comprises thousands of individual reefs and islands, making it a UNESCO World Heritage Site and an area of immense biodiversity. The sheer size of the Great Barrier Reef allows it to support a vast array of marine life, including numerous species of corals, fish, mollusks, and crustaceans, contributing to its importance ecologically and economically as a major tourist destination.

The Belize Barrier Reef, while significant and the largest in the Western Hemisphere, does not match the scale of the Great Barrier Reef. Similarly, the Red Sea Reef and the Andaman Sea Reef are important coral reef systems but are smaller in size and do not compare in terms of area or biodiversity with the Great Barrier Reef. Therefore, the Great Barrier Reef stands out as the largest in scale and ecological importance.