The Great Barrier Reef is Australia’s greatest treasure. It is the world’s largest coral reef system spanning more than 2000 Km between the Queensland coast and the western edge of the Pacific Ocean. It is one of the most mesmerizing seven wonders of the natural world. It is the only living thing visible from space. The Great Barrier Reef appears to be about 500,000 years old and supports a diversity of marine life.  It is like an underwater city comprising of about 2,900 separate reefs and 900 islands.

The Great Barrier Reef comprises of corals or polyps which are jelly-like soft-bodied carnivores which has stinging cells that grab prey such as small fish. Corals secrete limestone to make hard skeletons limestone cups into which they can pull themselves and hide from their predators. The corals occur in large colonies and are linked by tissues. The reef has water temperature ranging from 18 – 33 °C. The saline and clear water through which the light penetrates provide an ideal environment for over 1500 species of fish, 4000 mollusk species, 360 species of hard corals and 400 species od sponge corals live on the Reef. It is the breeding area for 30 species of whales and dolphins, porpoises, 6 species of sea turtles, 17 species of sea-snake, dugong (sea cow), shark and metallic-blue fish.

The Reef was established as a national park in 1975 and UNESCO selected it as a World Heritage Site in 1981. The coral reef with the magnificent coral collection and breathtaking natural beauty both below and above the water surface has become a popular tourist destination providing divers with the most spectacular underwater experience. Viewing of the reef is either by snorkeling, scuba diving, semi-submersible vessels, from a glass-bottomed boat, or catamaran. Over 1.6 million tourists visit this Marine Park every year which generates approximately AU$ 4-5 billion per year. There is a threat to the reef with increasing tourism due to pollution from boats and humans, walking on the reef and human carelessness.