Play outdoors one of the best-known beaches in Barcelona
Once home to the shanty-town of Somorrostro, Somorrostro beach is 522 meters of handicap accessible beach easily accessed from pretty much anywhere in Barcelona via a bus, metro, or bike (including Barcelona's public bike service, biking).
While this is not the beach for meditation or other "quiet" activities, it's a great place to play outdoors and soak up the sun without leaving the city proper.
Metro stop: Barceloneta or Cuitadella
Tram: Cuitdella-Vila Olímpica