Praia do Magoito
Just to the north of Sintra, close to the village of Magoito is the relatively quiet beach of Magoito (Praia do Magoito). To the south imposing cliffs rise straight up from the beach, leading the eye along the coast to Cabo da Roca, the westernmost point in continental Europe. As you can imagine, facing straight into the Atlantic Ocean the seas here can get pretty wild.
The beach itself comprises of a long stretch of golden sand dotted with numerous rocks. The sea here is a beautiful turquoise colour and is reputedly richer in iodine than any other beach in Europe.
For those with an interest in geology / natural history there is the "consolidate dune" at the northern end of the beach, by the main access. It is a solidified sand dune created by the action of sea and wind over the millennia.