Beaches

The metropolitan area of Lisbon offers many good beaches in a radius of 25 km. 
Best beaches, in the Lisbon Guide's opinion, are in Costa de Caparica. The line from Lisbon to Cascais offers good sandy beaches in a more urban style. Guincho beach is a more human untouched place, searchen by beach-nature lovers (wich include lots of surfers!).
 

Costa de Caparica

Fine golden sand, fresh air and a true beachy atmosphere attract legions of people on summer week ends. There is a stroll along the beaches, very nice for jogging fans. It is easy to spot the restaurant "O Barbas" (The beard guy) - the name comes from the facial aspect of its owner. This restaurant is a true Benfica (the football club) monument, as the beard guy is a big fan. Main speaciality is caldeirada, a traditional fish dish.
Back to the beach - beware of the sea! Strong waves and currents are not a problem to surfers, but it is sometimes dangerous.
How to get there?
By car: Cross 25th of April Bridge, direction South. Then turn right in exit "Caparica - Trafaria - Hospital" You'll get to the beach area after around 7 km.
By bus: In Praça de Espanha, take bus 153 of  TST. It takes about 45 minutes to Costa de Caparica.

Someone going from Lisbon to Cascais by the river/sea will pass a variety of beaches after Cruz Quebrada. Although still debating with some environmental problems, these are still a good place to be in. The Lisbon Guide advises a visit to Carcavelos
 

Carcavelos

With more than 1 Km of sand line and good transport acess, this beach attracts crowds of sun burning people in summer and legions of surfers all over the year. A pleasant stroll can take you from point to point along the sand, where you'll pass by lots of beach bars. Parking your car is easy in one of the many places available. There is a skate half pipe and a basket small field in the parking lot.
How to get there? From Carcavelos train station, go south direction 600m. Bus number 106 comes from Amadora and stops 200m away.
 

Rainha Beach

Downtown Cascais, this small hidden beach is a favourite for many locals. Very pretty.
 

Guincho

Integrated in Sintra-Cascais Natural Park, this well preserved beach attracts people looking for more natural environments. Surf lovers also come here hoping the usually strong winds help carving the perfect wave. If you are an unexperienced swimmer: beware of the water - it is many times dangerous and kinda cold. There are beautifull sand dunes formed above and the breeze is pure, sea temperated. Guincho is a must see, if you are a nature fan.
How to get there? There are buses from Cascais center. You can also go by the sea by bike or inline skates since there there is a proper road painted in red along the sea shore (8 Km from center of Cascais).