Background A lack of scientific knowledge of offshore habitats and species has restricted the expansion of the Natura 2000 network into the sea. Research in marine areas far from the coast is costly. Few organisations and institutions have the necessary means and capability to undertake such work. However, Member States were committed to providing the scientific information required to complete the marine Natura 2000 network at sea by mid-2008, or to provide a clear timeframe for achieving this. The biodiversity of Spanish waters is one of the highest within the EU, due to its biogeographic and oceanographic features. Its conservation is a priority for the Spanish government. Apart from marine reserves and coastal marine Natura 2000 sites, the only marine protected area in Spanish waters is El Cachucho, which was designated in 2008. The project will deal with 10 pre-selected marine areas covering 2.5 million ha. The Spanish government is the competent authority for the designation and appropriate management of these areas. Objectives The main objective of this project is the protection and sustainable use of biodiversity in the Spanish seas through the implementation of the Natura 2000 network. To this end, the project will ensure the necessary studies are carried out to complete the identification of the most representative marine areas around Spain. It also proposes to add at least 10 sites to the Natura 2000 network. The results will support any future revision of the Birds and Habitats Directives’ annexes and will contribute to the implementation and reinforcement of the marine international conventions applied in Spain – OSPAR and the Barcelona Convention. The project will follow a participatory approach including all the relevant institutions, NGOs and competent administrations. Eleven organisations will act in a co-ordinated way through scientific and steering committees to improve information on species, habitats and threats. All the data compiled will be included in a marine GIS, and guidelines for the management and sustainable use of the Natura 2000 network will be drafted. The project foresees the involvement of stakeholders (mainly fishermen) from the initial stages of the implementation of Natura 2000 at sea. Increased social awareness of the importance of conservation and the sustainable use of marine resources and of Natura 2000 will be attained through a significant dissemination campaign. Expected results: Increased scientific knowledge on habitats and species of the EU conservation directives (Habitats and Birds Directives) and regional marine conventions: size and location, characterization, threats and conservation status; Acquisition of all necessary information to formalise the Spanish proposal for the marine Natura 2000 network. At least 10 proposals will be completed and sent to Brussels; Guidelines for the management and monitoring of the marine Natura 2000 sites proposed will be approved in accordance with the framework of the Heritage Law passed in November 2007; Collaboration agreements will be drawn up between coordinating and associated beneficiaries for the project implementation; Consensus will be built between the socio-economic sectors involved in the conservation and management of the natural resources of the sea; Increased social awareness of the importance of conservation and sustainable use of marine natural resources and Natura 2000; Spain will be in a position to update the Habitats Directive and regional convention annexes; There will be a proposal for new marine protected areas under OSPAR and the Barcelona Convention.