Creation and effective management of marine protected areas (MPAs) have lagged behind those of protected areas on land, but they are just as important. The world urgently needs a comprehensive system of MPAs to conserve biodiversity and to help rebuild the productivity of the oceans. The aim of these guidelines is to help countries establish systems of MPAs as a key component of integrated management of coastal and marine areas and as part of their sustainable development. The various actions to make an effective MPA are set out, from early planning stages to implementation. These guidelines aim to help policy-makers, planners and field managers, whether working on conservation of nature or sustainable use of marine resources