A new study demonstrates that the recent mass coral bleaching on the Great Barrier Reef was not restricted to shallow depths, but also affected deep reefs. Although deep reefs are often considered a refuge from thermal anomalies, the new research highlights limitations to this role and argues that both shallow and deep reefs are under threat of mass bleaching events. Published today in the journal Nature Communications, the study focuses on the mass bleaching event in 2016 that caused the death of 30% of shallow-water corals on the Great Barrier Reef. It details how the impacts of this bleaching lessened over depth, but were still substantial on deep reefs.