The objective of this book is to provide a comprehensive overview of the legal basis, under international law and the relevant regional legal frameworks, for the establishment and further development of area-based conservation tools in the Mediterranean Sea, with a particular emphasis placed on the transboundary area-based conservation instruments available for the Adriatic and Ionian Seas. Specifically, the aim is to identify and analyze the concepts and functioning of both marine protected areas (MPAs), as traditional area-based tools enabling marine habitat and species conservation, and other effective area-based conservation measures (OECMs), as a more recent addition to the picture. Further, with a view to providing responses to the complex set of challenges raised by the variety of tools and levels of intervention, conclusions and ways forward are provided that identify practical implementation instruments through which a truly transboundary perspective may guide the development of protected marine spaces in the macro-region. An essential consideration in defining the ways forward lies in that the current trend towards the establishment of exclusive economic zones could soon become an incentive towards the adoption of a coherent and coordinated Mediterranean – and Adriatic and Ionian – network of transboundary area-based conservation tools. The book will be of interest to policy makers, practitioners, and academics with an interest in public international law, the law of the sea, and sustainable ocean governance.