The general objective of EXOCET/D is to develop, implement and test specific instruments aimed at exploring, describing, quantifying and monitoring biodiversity in deep-sea fragmented habitats as well as at identifying links between community structure and environmental dynamics. Onboard experimental devices will complement the approach, enabling experiments on species physiology. The EXOCET/D working fields include: video and acoustic imagery, in situ analysis of physico-chemical factors, quantitative sampling of macroand micro-organisms, in vivo experiments, integration of multidisciplinary data, implementation on European deep-submersibles and a final phase of technical and scientific validation