The biggest barrier reef in the world is the Great Barrier Reef, situated in the Coral Sea, off the coast of Queensland, Australia. It stretches over 2,300 kilometers and consists of approximately 2,900 individual reefs and 900 islands. This incredible marine ecosystem is recognized as a UNESCO World Heritage site due to its extensive biodiversity, hosting thousands of marine species, including fish, corals, mollusks, and turtles. The Great Barrier Reef is a significant destination for tourism and research, but it faces threats from climate change, pollution, and coral bleaching, highlighting the need for conservation efforts to protect this natural wonder.