Hosted by the British Antarctic Survey the Antarctic Digital Database (ADD) has been designed as the premier source of vector topographic data for scientific GIS (geographic information systems) applications and educational uses. It is the product of an international collaborative project under the auspices of the Scientific Committee on Antarctic Research (SCAR). Originally published on CD, this updated online version (4.1) provides access to cartographic material published by 11 nations and to the first seamless digital map of Antarctica compiled from these data. It is an essential resource for environmental scientific research, including information on conservation areas, bird populations and satellite altimetry. Access is through electronic registration, free of charge for non-commercial purposes. The downloaded data requires unzipping.