The world's largest coral reef is located in the Coral Sea off the coast of Australia. It is the Great Barrier Reef, which stretches over 2,300 km along the Queensland coast. It is home to a wide variety of marine life, including over 1,500 species of fish, 400 species of coral, and 4,000 species of mollusk. It is the largest living structure on Earth and can even be seen from space.