International cooperation is a must to achieve the goal of sustainable development, since only through cross border actions’ complex issues like environmental degradation can be faced. Supranational initiatives and shared objectives are the only path for getting a durable and effective green strategy, which transcends boundaries or governments and fosters a common effort for sustainability through networking. The European Neighborhood and Partnership Instrument (ENPI) aims at reinforcing cooperation between the European Union (EU) and partner countries’ regions placed along the shores of the Mediterranean Sea. To this extent, MESP (Managing the Environmental Sustainability of Ports for a durable development) can be considered as a typical cross border cooperation project, willing to create a sustainable environmental management of port in northern and southern shores of the Mediterranean basin. This has been achieved through the development of specific guidelines towards environmental sustainability and the collection of common tools, methodologies, good practices and innovations focused on pollution reduction that can be replicated in Mediterranean ports and further. This was possible through the creation of a strong cooperation network and long-lasting collaborations among partners and stakeholders such as harbour cities, port authorities, universities, research centres and scientific skills.