Two streams flow into each other at this quiet beach, one coming from a large valley where there is a large floodplain that is currently used for farming. In the immediate vicinity of the beach, you can see hydraulic devices that bear witness to the ancient human presence at the site. In bygone days, Boca do Rio was an important Roman villa. Today, traces can still be seen of frescoes and mosaics, bathhouses, warehouses and a fish salting and conserving factory, with two associated cemeteries, suggesting that there could have been a fishing port here. On the cliffs to the east (Ponta da Almádena), you can visit the Almádena Fortress and admire the breathtaking panoramic view over the coast. A small lagoon area usually forms at the mouth of the stream that flows on to the beach. If you follow its course upstream you will very possibly spot otters or traces of them.