The closest dog beach to Castelldefels is actually just over the municipal border in Gavà — Platja de les Marines, located between Carrer de Vandellòs and Carrer de Tamarit, a short walk from Castelldefels. This well-equipped dog zone covers around 1,000m² of fenced beach with direct sea access, dog showers, waste facilities, and supervised entry. Open from late May to late September, 8:30am–8:30pm daily, with a capacity of 75 dogs. Dogs must be microchipped to access the area. The beach is wide, sandy, and significantly less crowded than Barcelona's city beaches — making it a popular choice for dog owners in the Baix Llobregat area. Easily reached by the R2S train from Barcelona — alight at Castelldefels Platja station.