The Great Barrier Reef is located off the northeastern coast of Australia. The barrier reef is the largest coral reef in the world and consequently is the largest living structure on the planet. Other types of reefs include fringing reefs and atolls.
Coral reefs are delicate ecosystems and are threatened by warming oceans brought on by present day global warming. Warming seas lead to coral bleaching; a phenomenon where corals release their symbiotic algae, turn white and die.