About 40% of the area of the Site corresponds to characteristic biotopes of sandy coasts (beaches, dunes and pine forests on sands). The rocky coast has a smaller representation (<5%), the same happens with the estuaries, whose coverage will be of the same order of magnitude. It is, however, in the municipality of Viana do Castelo that the rocky coast has a greater representativity, being this type of coast predominant to the north of the river Lima.
At the southern limit of the county of Viana do Castelo, the river Neiva appears, which cuts through the dune system and gives rise to a small estuary. Due to its small size, it is not of great importance as a biotope forming agent. Its margins are intensively occupied by agriculture, leaving little room for the expression of the biological communities normally associated with this type of watercourse.