The Great Barrier Reef along the northeast coast of Australia is the largest coral formation in the world, covering more than 365,000 square kilometers. Within it exists a unique underwater environment that is continually evolving: the coral itself can vary greatly from one region of the reef to another as it adapts to varying conditions of light, surf, and temperature. In this program, marine biologists and photographers explore the reef using specialized underwater cameras to investigate the diverse and interdependent plants and animals that live there. The program also documents the annual spawning of coral and the geological and biological forces that make it possible for coral reefs to survive. Coral reefs around the world are incredibly fragile; many are endangered by overfishing and excessive use by humans.