Overview

The Great Barrier Reef is inscribed on the World Heritage List, recognising its outstanding universal value. Outstanding universal value means the property’s cultural and/or natural significance is ‘so exceptional as to transcend national boundaries and to be of common importance for present and future generations of all humanity’.

Location and size

The Great Barrier Reef World Heritage Area covers 348,000km². It includes marine areas and all the Great Barrier Reef islands contained inside its boundary. It is slightly larger than the Great Barrier Reef Region, as it includes some additional areas, such as the islands of Queensland and certain coastal areas associated with port activities. The spatial extent of the World Heritage Area has remained generally unchanged since its inscription.

World Heritage values

The Great Barrier Reef meets all four World Heritage natural criteria. The short titles used in the Great Barrier Reef Outlook Report 2024 for these criteria  are:

• Natural beauty and natural phenomena (criterion vii)
• Major stages of Earth's evolutionary history (criterion viii)
• Ecological and biological processes (criterion ix)
• Habitats for conservation of biodiversity (criterion x).

The Great Barrier Reef was inscribed on the World Heritage List in 1981. It was the first coral reef ecosystem listed and is now one of 51 marine World Heritage areas.

Differences between the Great Barrier Reef Marine Park, Region, World Heritage Area and Catchment (Table 1.1 from the Great Barrier Reef Outlook Report 2024).

The square kilometres of each area is approximate. Terms relating to ports are described in the Outlook Report.

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• This map shows examples of the differences between the boundaries of the Marine Park, Region and World Heritage Area. It also includes a Queensland island (Goold Island) that is positioned within, but not part of, the Region.

Natural beauty and natural phenomena (criterion vii)

The Great Barrier Reef was inscribed as a World Heritage property as an example of superlative natural beauty above and below the water. The property is noted to have spectacular scenery, creating an unparalleled aerial panorama of seascapes, and it is visible from space.

The significant elements that make up the Reef’s superlative natural phenomena include:

• annual coral spawning
• migrating whales
• nesting turtles
• significant spawning aggregations of many fish species.

Its aesthetic attributes above and below the water closely align with the Reef’s natural beauty. The property’s aesthetic values rely heavily on the condition of the Reef’s ecosystem.

Major stages of Earth's evolutionary history (criterion viii)

The Reef has evolved over millennia but is relatively young in geological terms. The continental shelf upon which the Reef has formed was mainly in place by approximately 2.6 million years ago. However, true reef growth, comparable to the modern reef, occurred earlier than approximately 450,000 years ago.

Since then, there have been at least six phases of reef growth during periods when interglacial sea levels inundated the continental shelf, punctuated by six periods of emergence when sea levels fell during glacial periods. In the context of Earth’s evolutionary history, long-term active calcification and accretion, which are important ecological and biological processes, add to its outstanding universal value.

Ecological and biological processes (criterion ix)

Ecological and biological processes form part of the Reef’s outstanding universal value. The Great Barrier Reef’s global significance is underpinned by the form and structure of its organisms, as well as the interconnectedness of the Reef’s complex physical, chemical and ecological processes.

Significant diversity of reef and island morphologies reflects ongoing geomorphic, oceanographic and environmental processes. Ongoing erosion and accretion of coral reefs, sand banks and coral cays combine with similar processes along the coast and around continental islands.

Extensive beds of Halimeda algae represent active calcification and accretion over thousands of years. Biologically, the Reef’s unique diversity reflects the maturity of an ecosystem that has evolved over millennia. Evidence exists for the evolution of hard corals and other fauna.

Ongoing ecological processes occur, such as upwellings, larval dispersal, and migration. Dynamic oceanic currents influence complex cross-shelf, longshore and vertical connectivity. Vegetation on the cays and continental islands exemplifies birds’ important role in seed dispersal and plant colonisation.

Habitats for conservation of biodiversity (criterion x)

The Reef’s biodiversity, with its vast network of habitats and range of species, is an important part of the Reef’s outstanding universal value. It is home to tens of thousands of marine and terrestrial species, many of which are of global conservation significance. The reef’s coral diversity is high — more than 1200 species of hard and soft corals. Six of the world’s seven species of marine turtle occur in the Great Barrier Reef. As well as the world’s largest green turtle breeding site at Raine Island, the Reef also includes many regionally important marine turtle rookeries. The continental islands support thousands of plant species, while the coral cays also have their own distinct flora and fauna. The Reef contains large ecologically important inter-reefal areas and supports half the world’s diversity of mangroves.