Graphs of global sea levels around the time of the poorly understood Last Glacial Maximum (27,000 to 20,000 years ago) previously showed stable ice sheets for about 10,000 years before the ice slowly started to melt. New analysis of the first Great Barrier Reef samples covering the time 22,000 years ago to 19,000 years ago finally adds detail to that period, providing valuable insights for models of climate and ice sheet dynamics.