Sydney Harbour is a long way from the Great Barrier Reef but is surprisingly home to scleractinian (hard) corals. Despite the extreme environmental conditions (low temperatures, low light) corals thrive here. Extreme environments may become the ‘norm’ for reefs and act as refuge environments, as coral reefs are at risk from pollution and global warming. Understanding how the Harbour corals are thriving in Sydney could enable us to better predict the future of coral reefs.