The Baltic Sea ecosystem is subject to a wide array of societal pressures and associated environmental risks (e.g. eutrophication, oil discharges, chemical pollution, overfishing and invasive alien species). Despite several years of substantial efforts by state and non-state actors, it is still highly unlikely that the regionally agreed environmental objectives of reaching “good environmental status” by 2021 in the HELCOM BSAP (Baltic Sea Action Plan) and by 2020 in the EU Marine Strategy Framework Directive (MSFD) will be met. This chapter identifies key research topics, as well as presents analytical perspectives for analysing the gap between knowledge and action in Baltic Sea environmental governance. It does so by outlining important tr...