Across the river from Lisbon and again across the water from Setubal lies the Tróia Peninsula, a 20 km long spit of sand that stands between the Sado estuary and the Atlantic Ocean. Comporta is located at the southern end of this spit with little but sand dunes and pine forest beyond.
Despite being only an hour, for the time being, the Tróia Peninsula, and Comporta remain off the radar. This means miles of uncrowded, powdery white sand in either direction and no worries about finding somewhere to park. Given its location in the relative backwaters of the Alentejo and the fact you've never heard of it you might expect the Praia da Comporta to be somewhat backwards - this is not the case. There is something of a laid back, groovy scene at Comporta with a couple of trendy restaurants right on the beach.
The charms of the Tróia Peninsula haven't gone unnoticed and towards the northern tip there has been a fair bit of development over recent years. It is easily reachable by ferry from Setubal although many of the visitors don't make it quite as far as Comporta.