Charles Darwin’s theory for the evolution of coral atolls triggered a century-long research project to test his theory. Australia’s Great Barrier ReefGreat Barrier Reef featured in debates about how reefs evolved, leading to the surprising discovery that corals have colonised the same limestone platforms off northeastern Australia over and over again for the past 20 million years. Today, coral reefs are at risk from warming ocean temperatures caused by anthropogenic climate changeClimate change. Surprisingly, our knowledge of the true distribution of tropical coral reefs is far from perfect. Even though most reefs can be mapped by satellites, other reefs remain hidden such as those in the Gulf of CarpentariaGulf of Carpentaria. The bleaching of corals is happening more and more often as the ocean warms, and we must ask: Has a tipping pointTipping point been passed? Will we be able to save the coral reefs?