Hypoxia has become a world-wide phenomenon in the global coastal ocean and causes a deterioration of the structure and function of ecosystems. Based on the collective contributions of members of SCOR Working Group #128, the present study provides an overview of the major aspects of coastal hypoxia in different biogeochemical provinces, including estuaries, coastal waters, upwelling areas, fjords and semi-enclosed basins, with various external forcings, ecosys-tem responses, feedbacks and potential impact on the sustainability of the fishery and economics. Keywords: Hypoxia, Coastal hypoxia, Ecosystems, Biogeochemical provinces, Coastal areas.