The Great Barrier Reef is the world's largest coral reef system, composed of over 2 900 individual reefs and 900 islands stretching for 2,600 kilometres (1,616 mi) over an area of approximately 344,400 square kilometres (132,974 sq mi). The reef is located in the Coral Sea, off the coast of Queensland in northeast Australia.

 

 

 

The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. The Great Barrier Reef supports a wide diversity of life, and was selected as a World Heritage Site in 1981. CNN has labelled it one of the seven natural wonders of the world. The Queensland National Trust has named it a state icon of Queensland.

A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as overfishing and tourism. Other environmental pressures to the reef and its ecosystem include water quality from runoff, climate change accompanied by mass coral bleaching, and cyclic outbreaks of the crown-of-thorns starfish.

 

 

The Great Barrier Reef supports a diversity of life, including many vulnerable or endangered species, some of which may be endemic to the reef system. Thirty species of whales, dolphins, and porpoises have been recorded in the Great Barrier Reef, including the dwarf minke whale, Indo-Pacific humpback dolphin, and the humpback whale. Large populations of dugongs live there.

Six species of sea turtles come to the reef to breed – the green sea turtle, leatherback sea turtle, hawksbill turtle, loggerhead sea turtle, flatback turtle, and the olive ridley. The green sea turtles on the Great Barrier Reef have two genetically distinct populations, one in the northern part of the reef and the other in the southern part. Fifteen species of seagrass in beds attract the dugongs and turtles, and provide a habitat for fish.

 

The most common genera of seagrasses are Halophila and Halodule. Salt water crocodiles live in mangrove and saltmarshes on the coast near the reef. Nesting has not been reported, and the salt water crocodile population in the GBRWHA is wide-ranging and with a low population density. Around 125 species of shark, stingray, skates or chimera live on the reef, including the irukandji jellyfish.

 

Close to 5,000 species of mollusc have been recorded on the reef, including the giant clam and various nudibranchs and cone snails. Forty-nine species of pipefish and nine species of seahorse have been recorded. At least seven species of frog can be found on the islands. 215 species of birds (including 22 species of seabirds and 32 species of shorebirds) are attracted to the reef or nest or roost on the islands, including the white-bellied sea eagle and roseate tern.

 

Most nesting sites are on islands in the northern and southern regions of the Great Barrier Reef, with 1.4-1.7 million birds using the sites to breed. The islands of the Great Barrier Reef also support 2,195 known plant species; three of these are endemic. The northern islands have 300-350 plant species which tend to be woody, whereas the southern islands have 200 which tend to be herbaceous; the Whitsunday region is the most diverse, supporting 1,141 species. The plant species are spread by birds.

 

 

Due to its vast biodiversity, warm clear waters and its accessibility from the floating guest facilities called 'live aboards', the reef is a very popular destination for tourists, especially scuba divers. Many cities along the Queensland coast offer daily boat trips to the reef. Several continental and coral cay islands have been turned into resorts, including the pristine resort island of Lady Elliot Island.

As the largest commercial activity in the region, it was estimated in 2003 that tourism in the Great Barrier Reef generates over billion annually. (A 2005 estimate puts the figure at AU$5.1 billion.) Approximately two million people visit the Great Barrier Reef each year. Although most of these visits are managed in partnership with the marine tourism industry, there are some very popular areas near shore (such as Green Island) that have suffered damage due to overfishing and land based run off.

A variety of boat tours and cruises are offered, from single day trips, to longer voyages. Boat sizes range from dinghies to superyachts. Glass-bottomed boats and underwater observatories are also popular, as are helicopter flights. By far, the most popular tourist activities on the Great Barrier Reef are snorkelling and diving, for which pontoons are often used, and the area is often enclosed by nets. The outer part of the Great Barrier Reef is favoured for such activities, due to water quality.

Management of tourism in the Great Barrier Reef is geared towards making tourism ecologically sustainable. A daily fee is levied that goes towards research of the Great Barrier Reef. This fee ends up being 20% of the GBRMPA's income. Plans of management are also in place for the popular tourist destinations of Cairns and the Whitsunday Islands, which account for 85% of the tourism in the region. Policies on cruise ships, bareboat charters, and anchorages limit the traffic on the Great Barrier Reef.