Parque do Núcleo de Interpretação da Duna da Cresmina
Time Out says
There are protected areas all over the world (and quite rightly so). The Cresmina Dune is one such place. You are not allowed to walk on the sand, but there are several boardwalks that allow you to explore the dune at your leisure. You can start at the Cresmina Dune Visitor Centre (Núcleo de Interpretação) where you can join a guided tour or pick up a leaflet describing the local flora and fauna and then walk all the way to Guincho. Before or after your walk, you can sit on the terrace with its views of the Serra de Sintra and of the sea, and order a salad, a crepe or toasted Scandinavian bread, all washed down with natural fruit juice.