This Greenpeace report sets out the argument for the urgent establishment of a network of marine reserves across the Mediterranean Sea to safeguard its productivity, its marine life and its ecosystems for the many millions of people who rely on it for their health and wellbeing - now and in the future.The Mediterranean Sea is a rich and diverse environment, home to many unique species and important ecosystems. Being an enclosed sea, and the majority of the Mediterranean being beyond the control of any one country, it truly represents a shared resource - and a shared responsibility - for the region.The Mediterranean Sea is threatened by many damaging human impacts, including over-fishing, destructive fishing techniques, pollution and climate change. Steadily, these are degrading the shared resource and treasure that the Mediterranean Sea represents. A network of large scale marine reserves will represent a shift in the balance of human impacts, from damage and harm to protection and conservation. This network must cover a representative range of marine ecosystems, both in coastal waters and on the high seas. Greenpeace believes that in the face of the damage that has been done to the Mediterranean, this network of marine reserves must cover around 40% of the Mediterranean Sea in order to protect it for generations to come. Because it is virtually enclosed and its habitats inter-connected, the Mediterranean Sea is a prime example of why marine management must take account of whole ecosystems, not single species or areas. A marine reserve network will create a sound basis upon which to build sustainable, precautionary and ecosystem-based management of the Mediterranean's marine resources.Experience of marine reserves elsewhere in the world has shown an increase in the number, size and diversity of species within the reserves. They therefore represent our most valuable tool in conserving biodiversity and making ecosystems more resilient to change or damage. This, combined with sustainable management, also brings benefits of precaution and insurance to fisheries management for the surrounding seas. Marine reserves also have many other positive benefits for science, education and recreation. Although agreements and commitments have been made at international, regional and national levels to protect the Mediterranean Sea, progress towards developing a network of marine reserves is still lacking. Agreements and commitments are meaningless without action, and action towards a network of marine reserves requires political will. Mediterranean countries must work together to protect the Mediterranean, our shared resource and treasure.