The Ria de Alvor (Alvor Estuary) is situated in the Algarve, Portugal, between the towns of Lagos and Portimão. Its 1700 hectares comprise the estuary, dunes, marshes and salt-pans, as well as the Quinta da Rocha and Abicada peninsulas with their mixed habitats of brushwood, forest and agricultural land. 

It was designated a Natura 2000 site (PTCON0058) due to the presence of species and habitats that are a European priority.

Although the Ria de Alvor is a relatively small area within the scope of the Natura 2000 network in Portugal, its intrinsic value in terms of biodiversity deserves recognition (and was a contributing factor in its classification as a Natura 2000 site):

• the existence of 19 habitats of interest to the community (Annex I of the Habitats Directive), including three priority habitats (1150 – Coastal lagoons; 1510 – Mediterranean salt plains; and 2130 – Fixed dunes with herbacious vegetation)
• also 6 species listed in Annex II of the same directive, including one species that is a conservation priority (1695 – Thymus camphoratus, as well as: 1639 – Limonium lanceolatum; 1726 – Linaria algarviana; 1355 – Lutra lutra; 1304 – Rhinolophus ferrumequinum; 1221 – Mauremys leprosa)
• as well as these, 273 species of bird, 500 species of vascular plant, 500 species of moth, 75 species of butterfly, 200 species of coleoptera (based on just a two week study), and 104 species of ictiofauna
• it is the most important wetland area within the Algarve and constitutes the last green, undeveloped area of this coastline
• it is a highly important ornothological point of passage on the East Atlantic migratory corridor
• the Ria de Alvor is a small area with delicate environmental balances to maintain, but is hugely valuable as a catalyst for quality tourism with enormous economic potential for the whole of the Algarve