Portinho da Arrábida Beach, for me the beautiful beach in Portugal.
Portinho da Arrábida in Serra da Arrábida, Setúbal is part one of the most beautiful bays in the world http://world-bays.com/setubal-bay/ with clean ocean waters, the unique mediterranean flora by the Arrábida Mountain and the estuary of Sado River you can enjoy the beautiful beach and the amazing view from the top of the mountain where you can see, depending the place you are, Setúbal, Tróia Peninsula and from there in a clean day you can see a beach with 65 km long that goes from Tróia till Sines.
Photos from http://joanofjuly.com/