Guide to the Great Barrier Reef

A visit to the Great Barrier Reef is on many people’s bucket-lists and it is no wonder why. Here is everything you need to know about this remarkable marine ecosystem, from how it’s formed to how you can see it for yourself.

Great Barrier Reef

One of the world’s most incredible natural phenomena, the Great Barrier Reef is a diverse marine wonderland and the largest living structure on earth. Comprising beautiful coral reefs, unspoiled islands and sandy corals cays, it provides protective homes for thousands of sea creatures. More than that, it guards coastlines against extreme weather, purifies the ocean waters, absorbs carbon dioxide from the atmosphere, and offers the best snorkelling and diving experiences on the planet.

A brief overview

A vast, complex, living network, the Great Barrier Reef stretches over 2,300 kilometres along Australia’s eastern coast, from Cape York in the north of Queensland, to Bundaberg in the south. Covering 348,000 square kilometres, the Great Barrier Reef comprises almost 3,000 individual coral reefs and 900 islands and is visible from space. To give you an idea of scale, the entire reef system is roughly the same size as Germany.

Added to the list of UNESCO World Heritage sites in 1981, the Great Barrier Reef contains greater biodiversity than any other World Heritage site. The reef is home to:

  • About 1,500 species of fish
  • 400 species of coral
  • 4,000 species of mollusc
  • 240 species of bird
  • 134 species of sharks and rays
  • 30 species of marine mammal including whales, dolphins and the vulnerable dugong
  • 6 species of sea turtle

With such an extensive range of creatures calling the reef home, this means that the Great Barrier Reef is of enormous scientific and environmental importance.

What is a coral?

What is coral?

The structures that make up a coral reef do not appear by chance; they are built by billions of tiny organisms called coral polyps. These mini builders have small, sac-like bodies with emerging tentacles. As the polyps absorb the calcium and carbonate ions from the seawater around them, they deposit these minerals to create a hard outer skeleton to protect their soft bodies. This is how the rock-like structure of a coral is formed. Over thousands of years, new polyps attach to the reef, adding to the rocky outcrops and building them into the structures we see today. Some of the corals could be hundreds of thousands or even millions of years old!

When thinking of a coral reef, one of the main images that is conjured up is that of bright colours. Surprisingly, these colours do not come from the corals. Instead, they come from algae (called zooxanthellae). Polyps have clear bodies and the millions of zooxanthellae that live inside them give them their wonderful colours. The algae also feed the coral. They take energy from the sun, convert it to energy, and then feed it to the polyp that provides it with a home. A perfect symbiotic relationship!

Most people will see a coral reef during the day, but the corals themselves are actually nocturnal. Under the cover of darkness, the polyps extend their long tentacles and capture tiny floating animals called zooplankton to feed on. They also breed at night. Once a year, following cues from the lunar cycle, they spontaneously release clouds of eggs and sperm that float through the ocean, eventually settling and forming new corals.

What is a Barrier Reef?

There are 4 classifications of a coral reef: a fringing reef, an atoll, a patch reef, and a barrier reef. Fringing reefs lie close to shorelines and are the most common, whereas atolls are rings of coral that form in the open ocean. A patch reef lives up to its name; it looks patchy. We find these small sections of a coral reef in shallow water, separated from others by rings of sand. Barrier reefs are very different. They run parallel to a coastline, separated from the mainland by a large, deep stretch of water. The Great Barrier Reef is the largest example of this on earth.

The Islands

Islands of the Great Barrier Reef

Emerging from the ocean along the Great Barrier Reef are several stunning islands. Some of these are coral cays (low, sandy islands that have been formed by sediment deposits), and others are large islands with hilltop lookouts and beautiful rainforests. Many of the islands are national parks and make an incredible backdrop for day trips and holidays, as well as providing a habitat for thousands of different animals.

In the heart of the Great Barrier Reef lies the 74-island archipelago of the Whitsunday Islands. Arguably the most well-known collection of islands along the reef, these protected isles showcase scenery that can only be described as a paradise. Their clear waters, glistening white beaches and diverse wildlife offer visitors a plethora of unforgettable experiences from snorkelling and diving to hiking and (for the more daring visitor) skydiving.

Each reef island has a special charm and character. Raine Island in the far north is the world’s largest green turtle breeding site and Heron Island, which lies much further south, is an eco-paradise that is also a favourite nesting place for turtles. Unspoiled Fitzroy Island is a mountainous national park that supports a rainforest oasis and fringing reefs, and the tiny coral cay of Green Island provides a diverse collection of beaches, rainforest and reef, all centred around a 15-hectare land mass.

Not only is each island surrounded by incredible marine animals, but they also play host to a myriad of birdlife that nest among the extensive native plant life that grows there. See sooty terns at Michaelmas Cay off Cairns, search for the rare red-tailed tropicbird and Herald Petrel on Raine Island and look out for brown boobies at Low Isles.

The reef is under threat

It is a well-known fact that the Great Barrier Reef is under threat. Global warming poses the biggest risk to the reef, but other factors such as shipping, coastal development, tourism, and crown-of-thorn starfish outbreaks also play a part.

One of the most well documented problems facing the reef is coral bleaching, which has occurred on a dramatic scale multiple times over the last few years. As global temperatures rise and conditions change, corals experience bleaching. Bleaching occurs when coral polyps expel the algae that live within their tissues. This is because the algae, which are very temperature sensitive, photosynthesize at a faster rate, producing a toxin that the polyp cannot tolerate. Since the algae give the coral their colour, no algae mean a bleached white reef. And because the algae also feed the polyps, many corals eventually die.

The Great Barrier Reef protects coastlines from weather systems and waves coming from the open ocean. The algae that live in the polyps also absorb carbon dioxide from the atmosphere to offset climate change. With it playing such a massive role in the health of the planet, it is essential that the Great Barrier Reef is protected.

How the reef is being protected

Thankfully, huge efforts are being made to protect the Great Barrier Reef. Conservation is the main aim of the Great Barrier Reef Marine Park, and the Australian Government has made reef protection one of their top priorities. With commitments to decrease sediment runoff from the mainland, long-term sustainability plans, and a $200 million yearly investment in the reef, the Queensland and Australian Government are not taking the health of this ecosystem lightly.

One of the most exciting ways in which conservation is being ensured is by planting lab-grown, baby corals onto the reef. Scientists at the Australian Institute of Marine Science have developed a new hybrid coral that is intended to be a more resilient variety, able to withstand the changes in the sea. As global warming continues to affect the conditions on the reef, researchers hope that these new species could survive increased temperatures and even elevated acidity levels.

Tourism is listed as a threat to the Great Barrier Reef, but it also contributes to its protection. With 2 million visitors every year, the $5-6 billion which tourism generates plus the environmental management charge that every visitor pays ensures that the money that goes to saving the reef is enormous. And the more people that visit the reef and fall in love with it, the more will be committed to its preservation.

How to see the reef

If you want to see the Great Barrier Reef for yourself, then there is a myriad of ways to do so. Whether you want to dive beneath the waves at a remote reef location, walk out to the corals from an island beach, or simply gaze across the crystal-clear waters from a hill or boat deck, you will have no end of choices. Here are some of the many ways you can experience the stunning beauty of the Great Barrier Reef:

  • Snorkelling and diving

    Snorkel at the Great Barrier Reef

    One of the best ways to see the abundant life beneath the waves is by trying snorkelling and diving on a boat tour. Cairns is a popular launch point that sees boats travelling to several individual reefs. Tours normally include snorkelling as a part of the package, but if you want to upgrade to a scuba diving experience, then these opportunities are available on board. Even if you have never dived before, there are beginner dives available, allowing you to swim amongst the beautiful corals accompanied by an experienced guide.

    You can also snorkel straight from the beach at many of the islands of the reef.

  • Glass bottom boat

    Glass Bottom Boast Tour

    Classed among the 7 wonders of the world, the Great Barrier Reef deserves to be seen by everyone, even if you can’t get into the water. Glass bottom boats create a window into the astonishing aquatic world and are perfect for elderly visitors or those with small children. Night tours also operate, giving visitors the chance to see the coral polyps as they emerge from their stony houses to feed on passing creatures.

  • Trek to an island lookout

    To see the mosaic-like formation of the Great Barrier Reef, observing it from a high vantage point is a must. Since the reef is located several kilometres offshore, the best place to view it is from one of the islands that is nestled among it. Fitzroy Island, for example, has several hiking tracks that will take you to lookout points. You’ll trek through a rainforest on the way to the summit, walking through lush jungle and looking out for birds such as the Orange Footed Scrub Hens and searching for the flash of a Green Triangle Butterfly.

  • Boom netting

    Boom Netting

    A newer addition to the activities on the Great Barrier Reef. Boom nets hang from the back of boats and as the vessel cuts through the azure waters, participants can clamber onto it and zoom above the reef.

  • Activity pontoons

    Activity Pontoon

    These floating adventure parks remain at the reef and boats travel out to them daily. Featuring slides, observation decks and sea walking (plus snorkelling and diving), these action-packed pontoons provide you with several exciting ways to experience the wonder of the reef.

    All activities are intensely regulated and managed, ensuring a sustainable industry that does not harm the reef. Many activities also provide additional information to educate all reef visitors.

What you will see on the reef

The Great Barrier Reef is home to some mighty creatures including Australia’s Great Eight: whales (including humpback and minke), manta rays, clownfish, turtles, potato cod, giant clams, Maori wrasse, and sharks. With most of these creatures found on the reef year-round, there is a high chance that you’ll tick at least one of them off your list when you visit. And if you’re scuba diving, then your guide will be happy to point these out if they spot them.

You can trust that you will see a vast array of corals and countless fish and anemones when you explore the reef, but what you may not expect is how blue everything will appear. We’ve grown up with colourful images of the reef: bright fish darting in and out of multicoloured corals. But the reality is that the water absorbs many wavelengths of light and at a depth of 5m most of the colours apart from blue have been absorbed. Pictures taken on an underwater camera, however, can be corrected with a red filter, allowing you to see the reef in all its vibrant glory!

The Great Barrier Reef truly is one of the most surreal and enchanting places in the world. Watching vibrant fish dart in and out of a sprawling network of corals and anemones is a sight like no other. When you are in Australia, book on to a tour, experience this natural wonder for yourself, and play your part in protecting this spectacular marine ecosystem.

Explore the Top things to do in the Great Barrier Reef!

Related article: Facts about the Great Barrier Reef

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