This report is a contribution to the Strategic Environmental Assessment (SEA7) conducted by the Department of Trade and Industry (now Department of Energy and Climate Change). Occurrence of carbonate and other mounds in the SEA7 region of the Atlantic Margin. This report focuses on the distribution, classification and internal (seismic) structure of carbonate mounds to the west of Ireland and the UK within the SEA7 region and its general environs. It also provides an overview of the main results from ongoing research in EU 5th Framework projects such as GEOMOUND, ECOMOUND and ACES. Various models for the origin and growth of carbonate mounds have been proposed in the literature. These range from hydrocarbon seepage and nutrient models to oceanographic and current influences and are discussed. The report also provides a comprehensive bibliography of mound references, a map of mound locations and a compendium of relevant metadata from the region.