The complex system of marshy places, salt-pits, canals, puddles, creeks and charcas (big extensions without vegetation), located in the Castro Marim and Vila Real de Santo António municipalities, was the first Natural reserve of the Portuguese territory. Land, river (Guadiana) and sea mix together, giving origin to a strange but beautiful miscellany, stretching to the mouth with Ayamonte, on the other side, as background scenery. The grounds are fertile in original flora (limelight to the halophytic species) and, specially, in an exotic fauna (avifauna, fishes, crustacean, molluscs, amphibian and reptiles).

Located in Odeleite, Castro Marim, this dam was built in Ribeira de Odeleite, which is born in Serra do Caldeirão. As a curiosity, aerial photography shows the shape of a blue dragon.

Barrage located at the Ribeira de Beliche (hydrological basin of the Guadiana), in an intermediate area of serra, trees and furze-field. Conditioned leisure and sports activities.