Vamos à praia
One of the closest beaches to Lisbon is in the suburb of Oeiras, just due west. It's approximately a 20-30 minute train ride from Cais do Sodre.
One interesting aspect of this beach is the proximity of a huge fort - São Julião da Barra Fort. It makes for a wonderfully scenic background.


Santo Amaro de Oeiras beach
but the same mess with cars parked on the pavement
Oeiras train station
Torre de Belém