The Great Barrier Reef - the largest system of coral reefs in the world - is more than 2,000 km in length and comprises 2,900 separate reefs and 940 islands. Its high species diversity includes more than 400 species of coral, 4,000 species of molluscs, 1,500 species of fish, six species of turtles, 35 species of seabirds and 23 species of sea mammals.

The idea that the Great Barrier Reef should become a marine park was mooted as early as1963 by the Wildlife Preservation Society of Queensland. Concerns over the level of foreign fishing and tourism industries highlighted the lack of protection for the Great Barrier Reef in the 1960s. The prospects of oil drilling and limestone mining upon the reef were pivotal in initiating a campaign that culminated in the Great Barrier Reef Marine Park Act 1975 (Commonwealth), the legislative basis for the Great Barrier Reef Marine Park Authority.

The Great Barrier Reef was accepted for inclusion upon the World Heritage List in 1981, meeting all four of the natural heritage criteria. A multiple-use, protected area of 348,700 km², the Marine Park is the world's largest marine protected area, and is Australia's premier marine tourism destination.

Perceived pressures on the Reef include declining water quality in inshore areas, due mainly to elevated sediments and nutrients from changes of land use in coastal catchments; fishing (particularly trawling of the seafloor and overfishing of some reef species):coral mortality caused by outbreaks of the crown-of-thorns starfish (the causes of which still remain unknown): storm events: the threat of oil and chemical spills and ballast water introduced from shipping: and the effects of tourism.

About two million people visit the Reef and its adjacent coast annually and in recent years the number of visitors has been increasing by 10% each year (30% in the Cairns area).

The size of the GBR World Heritage Area, from the low water mark on the mainland coast to past the edge of the continental shelf, and from the tip of Cape York Peninsula to just north of Fraser Island, ensures that a highly diverse suite of habitats and environmental regimes at a range of spatial scales are represented in the one World Heritage Area. This habitat diversity gives rise to a vast number of species and ecological processes.

The Great Barrier Reef is one of the least anthropogenically disturbed coral reef systems in the world and most of it is still in a relatively good condition. There is photographic evidence of coral mortality on the tops of some inshore reefs but the evidence is patchy and not consistent on all reef tops for which historical photos are available. Possible causes include cyclones and increased sediments and nutrients.

Recent evidence also suggests that parts of some reefs in the Capricorn Bunker sector of the Great Barrier Reef are showing signs of degradation: hard coral and fish appear to be reduced compared with other parts of the Reef. The causes of this are unknown, but do not appear to be related to the crown-of-thorns starfish or to cyclones. Strong recovery of corals has been recorded in the most recent surveys. Elsewhere on the GBR, crown-of-thorns starfish have damaged nearly 20% of reefs, largely in the central one-third of the Reef. Damage in affected areas ranges from slight to very severe, and the extent and speed of recovery is likewise variable.

The Great Barrier Reef is managed by the Great Barrier Reef Marine Park Authority (GBRMPA), with the Queensland Department of the Environment responsible for day-to-day management. Oil drilling and mining are prohibited in the Marine Park. The establishment of the GBRMPA coincided with a significant period of expansion in tourism, particularly around Cairns. As a result, development and access for visitors has been planned and regulated within the context of a marine protected area. Use of the Great Barrier Reef is regulated primarily under a zone-based planning scheme intended to achieve sustainable use of coastal and marine resources. Among the challenges is that of harnessing co-operation for maintaining environmental protection, particularly in relation to pressures by coastal development, and increasing resident populations and tourist numbers. The involvement of state and local government bodies and industry is crucial to achieving this broad management goal.

While the agency approach has worked well on a case-by-case basis and has proved effective even in extremely complex projects -such as a now-defunct and removed floating hotel - it has sometimes proved difficult at a local level. For example, the development of strategic management plans for the Whitsunday and Cairns subregions has highlighted the problems of coordinated management and demonstrated the need for co-operative planning of regional tourism. These cases also reveal the complexity of issues that must be addressed if tourism, fishing, shipping, and assimilation of runoff from the land are to be sustainable in areas of high conservation value such as the Great Barrier Reef.