Maritime safety and security have become matter of concern for many States and for the international community as a whole. However, the existing international legal framework does not yet recognize maritime safety and security as specific and autonomous legal regimes, and the practice also mirrors the weakness and the fragmentation existing in the field. This Cost Action will take an in-depth look at current urgent maritime matters focusing on four main issues: i.e., shipping and marine environmental protection, new developments of economic activities at sea, maritime international security and border surveillance and, finally, protection of fragile and semi enclosed seas. Marsafenet aims to bring together experts in international law of the sea in order to increase the knowledge on these topics and to develop a common conceptual and methodological framework with the goal of contributing to fill the legal gaps and of transforming scientific results into feasible solutions for ensuring safety and security at sea. The Action is intended to foster the identification and exploitation of synergies between EU policies on maritime safety and security and to be complementary to the existing European cross-sectorial initiatives in this area, allowing the existing knowledge to be shared and enhanced within a structured comparative framework, with a view to disseminating findings at national and international level and identifying inputs for supporting the decision-making process in the field. In terms of societal implications, Marsafenet is aimed at facilitating the detection of solutions for old and new issues and criticalities, that may be implemented within the public realm (decision-makers, international institutions, international and national tribunals, EU institutions, etc.) and within the private sector (shipping sector, civil society, NGOs, etc.).