Although known since Antiquity, corals in deep, cold waters remained largely unappreciated and overlooked by the scientific community until the 1990s. The last two decades have seen a dramatic increase in our understanding of these diverse ecosystems alongside growing realisation that many cold-water coral habitats had been degraded by bottom trawling and are threatened by ocean warming and acidification. This paper discusses recent improvements in our understanding of cold-water coral ecology, taxonomy and biodiversity following a variety of advances from the application of predictive mapping to the use of molecular phylogenetic approaches. Since many cold-water coral ecosystems occur in deep-waters beyond national jurisdiction, conservation management measures are being developed through the United Nations and related conventions. All such management measures require not only international agreement but also monitoring and enforcement to ensure their success. © 2014 The Authors.