This book compiles the main findings of the multidisciplinary long-term research program developed in the continental margin of one of the more productive and unknown areas of the world oceans, Northwest Africa. The more than 25, 000 preserved fishes and benthic invertebrates and quantitative data collected in 342 trawling stations, the 267 oceanographic profiles, the 211 sediment samples and the 28, 122 km2 prospected by multi˗beam echo sounding allowed to obtain an overview of the amazing biodiversity of the demersal and benthic fauna inhabiting soft- and hard-bottom habitats, as well as the fascinating geomorphology and oceanography, hidden in the Mauritanian slope.