Great Barrier Reef Trivia
0Loading crowd target
0Loading crowd target
7correct to beat the crowd
46 free Great Barrier Reef trivia questions with answers — geography quiz, new questions added Sep 2026.
The Great Barrier Reef is the largest thing on Earth built by living creatures, a chain of 2,900 reefs and 900 islands running 2,300 km down the coast of Queensland that astronauts can pick out from orbit. This quiz starts with the numbers a beginner can enjoy (how long, how many reefs, which sea, which state) and works up to the geology: why Queensland was too cold for coral until 24 million years ago, why the living reef is only 6,000 to 9,000 years old, and what a 'wonky hole' is. It then meets the wildlife: 1,500 fish species, six kinds of sea turtle, dugongs grazing 15 species of seagrass, 30 kinds of whale and dolphin, mass coral spawning after the October full moon, and the crown-of-thorns starfish that eats it all. History gets its share with Cook's grounding in 1770, Matthew Flinders' naming, the wreck of HMS Pandora and 40,000 years of Aboriginal use, before the quiz turns to bleaching, farm runoff, shipping accidents, shark culling, the Reef 2050 plan and the reef's premature obituary in 2016. Every answer was checked against Wikipedia's articles on the Great Barrier Reef and its wildlife, and each question shows the sentence that supports it. Try our Australia, coral reefs and ocean quizzes next.
30 of 46 questions with answers and explanations. Play the quiz
Q 01The Great Barrier Reef lies off the coast of which Australian state?
Queensland
Queensland: it began as part of New South Wales and split off as a separate colony only in 1859.
Q 02The Great Barrier Reef Marine Park covers roughly the same area as which country?
Italy
Italy: in 2022 the Darumbal people were formally recognised as protectors of 36,606 square kilometres of it, the reef's largest agreement of its kind.
Q 03The reef is described as the world's biggest single structure made by what?
Living organisms
Living organisms: coral polyps built it, and though corals can look like plants, each polyp is an animal.
Q 04Which UNESCO list has the reef nearly joined?
World Heritage in Danger
World Heritage in Danger: UNESCO recommended it in 2021, but Australia's government lobbied successfully against the listing.
Q 05Which wildlife TV presenter died in 2006 after a stingray's barb pierced his chest while filming on the reef?
Steve Irwin
Steve Irwin: the attack was caught on film, but those who have seen the footage say it should never be shown.
Q 06Which navigator, who charted the reef in detail in 1802, called its collection of reefs the 'Barrier Reefs'?
Matthew Flinders
Matthew Flinders: on the same voyage he went on to sail right around mainland Australia, charting its coasts.
Q 07Cook's ship that struck the reef in 1770 was named what?
Endeavour
Endeavour: guns, ballast and stores were thrown overboard, the ship was hauled off two tides later, and repairs kept it beached for seven weeks.
Q 08Which Royal Navy ship, sent to hunt down the Bounty mutineers, sank on the reef in 1791?
HMS Pandora
HMS Pandora: it sank the morning after striking the outer reef, and 35 men died, among them four of the mutineers it had captured.
Q 09When seas were far lower, what lay where the reef now stands?
A coastal plain
A coastal plain: ice-age ice sheets had locked up so much seawater that the land under today's reef lay dry.
Q 10The reef's northernmost island, in the Torres Strait, is called what?
Bramble Cay
Lady Elliot Island, 1,915 km to the south-east, marks the other end.
Q 11Until about 25 million years ago, why could coral not grow off north-eastern Australia?
The water was too cool
Australia has been drifting north about 7 cm a year, and Queensland only entered tropical waters around 24 million years ago.
Q 12Which large sea snail is one of the few natural predators of the reef's coral-eating starfish?
Giant triton
Giant triton: it devours the starfish, spines and all, and the over-collecting of tritons is one suspected cause of the starfish's outbreaks.
Q 13Which ancient rainforest, often called the world's oldest, borders the Great Barrier Reef on Australia's north-east coast?
Daintree Rainforest
Q 21Mass coral spawning on the Great Barrier Reef is triggered by water temperature and which other natural cue?
The full moon
The full moon: on the nights after it, whole coral colonies release their eggs and sperm at once, filling the water like a snowstorm.
Q 22Which fingernail-sized box jellyfish, found in reef waters, can cause a painful and sometimes deadly syndrome?
Irukandji
Irukandji: in 1961 doctor Jack Barnes caught one and tested its venom on himself, his nine-year-old son and a volunteer lifesaver.
Q 23Which reef mollusc hunts by stabbing its prey with a venomous, harpoon-like tooth?
Cone snail
Cone snail: one species' venom gave rise to a painkiller used for severe chronic pain, and scientists are testing compounds from others.
Daintree Rainforest: in 2021 it was handed back to its Aboriginal custodians, the Eastern Kuku Yalanji people, who now manage it with the state government.
Q 14A 2009 campaign billed as 'the best job in the world' hired a caretaker for the reef's islands, based on which island?
Hamilton Island
Hamilton Island: the six-month caretaker role was really a campaign to promote the reef worldwide, and it came with a villa on the island.
Q 15In 2020 scientists found a detached reef in the Great Barrier Reef's northern waters; roughly how tall is it?
500 metres
500 metres: after seafloor mapping revealed it, scientists sent an underwater robot down to explore the new reef.
Q 16What is a 'wonky hole'?
A freshwater upwelling
The nutrient-rich freshwater can cause local eutrophication.
Q 17When the breeding female in a group of reef clownfish is lost, what usually happens?
The largest male becomes female
The largest male becomes female: the biggest non-breeding fish then becomes the new breeding male, and the others each move up a rank.
Q 18Which turtle nests on Raine Island in the tens of thousands?
Green turtle
Green turtle: after thousands of females died at the island's small sand cliffs, a rescue project reshaped its nesting beaches.
Q 19Which large seagrass-grazing marine mammals live in big populations on the reef?
Dugongs
Dugongs: they are the only marine mammals in Australia that live mainly on plants, and as they graze they leave telltale feeding trails through the seagrass.
Q 20Humpback whales that calve on the reef feed in which waters each summer?
Antarctic
Antarctic waters: they go there for krill, the small crustaceans that make up most of their diet.
Q 24Between 1.4 and 1.7 million of what use the reef's islands to breed?
Birds
Birds: they carry the seeds of many island plants, and far-northern Raine Island is considered the reef's most important seabird breeding site.
Q 25Which starfish preys on coral polyps and periodically devastates the reef?
Crown-of-thorns
Crown-of-thorns: its numbers periodically explode into huge outbreaks, and poor water quality is believed to make those outbreaks worse.
Q 26To cull the reef's coral-eating starfish, what do divers do to each one they find?
Inject it
Inject it: a jab takes seconds, while cutting a starfish up is slow and gets divers spiked.
Q 27In 2015 Australia announced a ban on dumping what inside the Great Barrier Reef Marine Park?
Dredge spoil
Dredge spoil: it is seabed dug out to create or deepen shipping channels, and one port project's spoil was sent to land instead of the park.
Q 28Coral bleaching happens when stressed corals lose what?
Their symbiotic algae
Their symbiotic algae: the algae give corals their colour and most of their food, so a bleached coral starves unless the algae return.
Q 29After the 2016 and 2017 mass bleaching, what plunged by about 89% on the reef?
New coral births
New coral births: so many breeding adults had died that too few were left to replenish the reef, and the mix of coral types changed.
Q 30Which US adventure magazine published an obituary for the Great Barrier Reef in October 2016?
Outside
Outside: its writer dated the reef '25 million BC–2016', after that year's bleaching had killed coral on a record scale.