The present chapter aims at analysing the relationship between the European Union and the future International legally binding instrument (ILBI) related to the conservation and sustainable use of marine biodiversity in areas beyond national jurisdiction - the high seas and the Area (deep seabed). The chapter will begin with a brief introduction detailing the manner in which the European Union has interacted with the international law of the sea. A particular focus will be placed on the difficulty that has arisen in distinguishing between the exclusive and shared competences of the EU in regard to the conservation of biological resources and the protection of the environment, at both a material and institutional level. Thereafter, the chapter will be two-pronged, elaborating upon the formal participation of the EU as regards the future instrument and the specificities of its substantive participation. Il also addresses the potential consequences for the Union of the adoption of such an agreement, in terms of its impact on EU maritime policy, on the exercise of its competences and on its participation in international institutions.