Great Barrier Reef Facts

This fact sheet for the Great Barrier Reef has been developed as an aid to all those who are confused by the mixture of information spread by various sources. Every attempt has been made to make them factual facts but no responsibility is offered nor accepted for the information contained herein. Should you have more up to date or accurate information I would appreciate hearing about it.


What is the Great Barrier Reef

It is a complex of about 3000 reefs, mainland islands, coral cays and all the water and sea floor in between them that extends 2300km from Lady Elliot Island in the south to Black Rocks in Torres Strait, to high water mark along the Queensland from Bundaberg to the tip of Cape York and northwards from here to PNG coast and to 500m along the eastern edge of the continental shelf. It is part of the Indo-Pacific bio-region and interconnected to it by the waters that flow freely between them all. It includes many forms of reefs including Fringing – on the mainland and mainland type islands, platform reefs, lagoonal reefs, ribbon reefs, deltaic reefs, linear reefs and coral islands or cays.


Be careful of the information on the GBR that is most commonly seen – it is put out by the Great Barrier Reef Marine Park Authority and it excludes all Torres Strait islands and reefs of the GBR.


Great Barrier Reef Region – is the area described in the GBR Marine Park Act 1975 and extends only to the tip of Cape York at 10º41’south and does not include those sections of the GBR in Torres Strait. It covers about 341,400sq km. See map.



Great Barrier Reef Province includes the Great Barrier Reef and the watersheds inland from Brisbane in the south to the western tip of Cape York, across Torres Strait and to the top of the watershed in PNG and then south to the NE tip of the Region and then includes all the Coral Sea Territories under Australia’s jurisdiction – covers almost 2million sq km. See map.


Great Barrier Reef World Heritage Area is the area included in the World Heritage Register in 1981 and includes all islands, seas and lands in the Great Barrier Reef Region. It covers 351,400 sq km.  See map.


Age of the GBR It was first formed about 500,000 years ago and has been dried out four times since then during ice ages so its present shape is a result of periods of growth and erosion. The last ice age ended about 8000 years ago and the sea level was about 130m lower 17,000 years ago.


Sea levels The sea levels have bounced up and down from around present levels to 130m lower during four low sea stands in the last 500,000 years. At the peak to end of the last ice age the sea rose from 130m to 0m in 10,000 years – at an average of 1.3cm per year. It rose 2m above present 5,000 years ago, fell to 0m, rose to 1.5m 3,500 years ago, fell to 0m, rose to 80cm 1,000 years ago and has now been relatively stable for the last few hundred years.


Numbers of Species etc. on the GBR – this is the whole GBR not the GBR Marine Park region  (> = more than)

As research and discovery systems improve many new species will be found. As you move further north towards the highest marine species diversity in the world in the Sunda Sea in Indonesia the numbers of species increases.

No one really knows but here are some best guesses – some quite accurate!

Mainland Islands           about 650

Coral Islands                about  350 -  also called cays and about 250 are vegetated

Island plants                 2195

Algae or Seaweeds        >500

Seagrasses                   15

Mangroves                    37                   

Hard Corals                  360

Soft Corals                   >60 Genera – No. species – who knows!!

Fish                             1500 including sharks and rays

                                  >150 species of sharks and rays

Molluscs                       >7000

Sea Turtles                   6 of the world’s 7 species nest on the GBR islands and coast

Sea Snakes                  >15

Crocodiles                    1 - Estuarine

Sea Birds                     22

Birds                           >200 including sea birds

Marine Mammals            >30

Echinoderms                 > 800 - feather stars, seastars, sea cucumbers & urchins

Worms                         >100,000

Bryozoans                    >500

Sponges                      >1500

Resorts                       5 on cays

                                18 on mainland islands

Beaches                     too many to count

Surfing breaks             on many of the outer reef fronts – very hard to get to and on                                 mainland south of Gladstone





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