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How The Great Barrier Reef was Formed

Updated Fri 14 Oct 2022

The Great Barrier Reef is the largest living ecosystem in the world. It has been around for many millennia and is continually growing and changing. It is a network that spans across 2,600km and is made up of corals, seagrass, islands, and cays that is make up the Great Barrier Reef Marine Park.

It is said that the reef dates back as much as twenty million years ago, with an ever-changing landscape and coastline. It has moved and morphed over the years and was first encountered by humans 40,000 years ago when Aboriginal and Torres Strait Islander peoples settled in the area. The current reef is about 6,000 to 8,000 years old and was formed after the last ice age began to recede and water levels and temperatures rapidly changed. 

Hardy Reef pontoon

The Formation Of The Reef

The Great Barrier Reef that we know today actually sits on what is the remains of the sediments of the Great Dividing Range, a huge mountain system. Corals began to form around the base of these mountains, which at the time were continental islands. Once sea levels began to rise, the growth of coral began to creep up the mountains, which were eventually completely submerged, leaving behind small islands, barrier reefs and atolls that we know and see today. The Whitsunday Islands, for example, are the remains of mountain tops that once towered over the region which are now surrounded by fringing reefs.

All reefs, including the Great Barrier Reef, begin to form with a single organism. A drifting coral polyp, expelled into the open sea by its parents, will come to rest on a stationary object, such as a rock or shell, where it will permanently attach itself to live its life. Here is where we see the humble beginnings of a reef. 

Turtle Swimming above the reef

 After they settle, polyps will begin to secrete a calcium carbonate, which hardens to form the bony white structure, or skeleton, that forms the shape of the coral itself. The polyp lives on the outside of this bony structure, where more of the same species will join it, becoming one organism. The polyps develop a relationship with algae, which is its source of food and its colour, which gives the coral its look. The healthy coral will continue to grow at a rate of about 5mm - 20cm per year, depending on the species, and grow best in temperatures between 21C and 29C.

Competition On The Reef

Other types of corals will settle in the same area, expanding and fighting for space and resources, until you eventually have a fully developed coral reef. Hard and soft corals are formed in similar ways and will eventually form on older, dead corals, always expanding and growing, changing the shape of the reef. Other marine plants and fish will begin to move into the same area, using the corals for food, protection or mating grounds, creating an ever-fluxing ecosystem. A coral reef can be likened to a towering forest that began from a single seedling - once just a small single plant, it can become a diverse and vast ecosystem.

The Great Barrier Reef is currently home to 1,500 species of fish, six species of sea turtles, 30 species of whales and dolphins and 411 species of hard coral. It is constantly changing before our eyes and is an ever-growing system. As visitors to the reef, it's important that you don't touch or interfere with corals and marine species on the reef, so they continue their natural life cycle and allow the reef to continue to be healthy and thriving.

Tours to the Great Barrier Reef

Cruise Whitsunday Reefworld

Spend a day out at the Outer Reef pontoon where you can snorkel and scuba dive with the tropical marine life. The pontoon is great for all ages and perfect for families! Enjoy a buffet lunch, visit the underwater viewing chamber and relax on the sun lounges on the top deck. 

reef world airlei beach

Cruise Whitsunday Reefsleep

Experience the reef in an entire new way! Spend a night sleeping under the stars on the Great Barrier Reef. This once-in-a-lifetime trip will see you sleeping in a comfortable, spacious swag for the night, waking up to the sounds of the reef coming to life, scuba diving and snorkelling!

reef slepp on great barrier reef


Kiana is a sailing yacht that will take you through the dreamy Whitsunday Islands and to the Outer Great Barrier Reef. Spend 2 nights and 3 days enjoying all that Kiana has to offer including freshly prepared meals, free scuba diving, snorkelling, spacious cabins and friendly crew!

The side of a white coloured sailing yacht in blue waters

Scenic flight over the reef

See the reef from an entirely new perspective as you fly above it! Take in the natural wonders and even land on Whitehaven Beach. The tour guides are insightful, friendly and keen to show you the region from the sky. Choose from a range of both helicopter tours and plane tours which will ultimately maximise your time in the stunning Whitsundays. 

A birds eye view of the Great Barrier Reef, taken from a plane

Ways to see the reef

For more information on the Great Barrier Reef or the Whitsundays, contact our friendly team on +61 74914 2425 or jump on our live chat today!

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