Ilha da Barreta
Situated within the Ria Formosa National Park, just off the coast of Faro the Ilha Deserta (Deserted island) lives up to its name. There are no permanent inhabitants here and the only significant structure on the whole island is the surprisingly popular O Estamine Restaurant at the eastern end of the island. The highly rated food here is prepared in the restaurant's solar powered kitchen.
The sandy island is around 7km (5 miles) long and only 600 metres wide at its widest point. One side backs onto the waters of the Ria Formosa lagoon with its maze of channels and prolific wildlife including a large colony of flamingos. To the other side is the wide blue ocean - Cabo de Santa Maria towards the eastern end of the island is the most southerly point in continental Portugal.
In between all this water are around 10 kilometres of beach. Even if this was on the mainland there would be plenty of room, given that it is on a deserted island you can probably find a kilometre of beach to yourself, which is one reason the beach is frequented by nudists (not officially).
All in all the Ilha da Barreta is a beach goers paradise and the main pastime appears to be sunning one's self with the occasional frolic in the sea. However there are other things to do such as explore the island and it is also a bit of hotspot for twitchers. Getting to the island is reasonably straightforward and costs around 10 Euros for a return boat trip from Faro or Olhao. The journey takes about 30 minutes each way.