The "Macrobenthos of the North Sea Project" is a joint initiative of the University of Amsterdam and ETI. In a series of five multimedia and interactive CD-ROMs - to be published at short intervals - a complete, up-to-date catalogue of the macrobenthic species in the shallow waters of the North Sea is given, together with reliable, standardized identification guides. Volume 1 presents detailed information on 525 species of Mollusca and Brachiopoda, including fully illustrated, computer-assisted pictorial keys, glossaries, interactive distribution maps, and hyperlinks throughout the entire text. This CD-ROM is an easy-to-use tool for all marine biologists - teachers and students alike - who are interested in identifying and monitoring the North Sea benthos.