From the lookout that is the castle of Castro Marim, built by the King Afonso III in 1242 and around which the town grew, one can admire the curious reticulated landscape, mixed estuary, salt marshes, pastures, ponds, streams and extensions without vegetation. Today, saliniculture, fish farming, agriculture and fisheries share the essentials of natural resource exploitation. Castro Marim serves as habitat or simple refuge for the large population of waterfowl such as the white stork and summer birds, such as the flamingo Phoenicopterus roseus and the dwarf tern Sternula albifrons.