This beach is a very small one. It's only a few stations away from Cais do sodre train station so you are getting there very fast. It's quiet and perfect if you only want to spend a few hours at the beach or don't want to drive so long.
You have to visit a beach in Lisbon especially in summer. Even if you only spend a weekend there you have time enough to go to this beach and enjoy sand , waves and an awesome view. It's really close to the station and many tourists also don't know that this beach exists.
You can also go swimming there!!