Yes, you can swim in Barcelona's beaches, and in 2026, the water quality is generally rated as "Excellent" or "Good" by EU standards. The city offers over 4 kilometers of coastline, with Barceloneta being the most famous (and crowded), while beaches like Bogatell and Mar Bella offer a more relaxed atmosphere. However, there are two major things to watch out for. First, after heavy rainfall, the city's sewage systems can overflow into the sea; local authorities often fly red or yellow flags for 24–48 hours after a storm, and you should strictly avoid the water during these times due to bacterial risks. Second, keep a sharp eye on your belongings; Barcelona's beaches are notorious for petty theft, and leaving a bag unattended while you swim is a high-risk move. In 2026, the city has also implemented stricter "smoke-free" zones on the sand. For the cleanest water, many locals recommend taking a short 20-minute train ride north to the town of Badalona or south to Castelldefels, where the water is often clearer and the sand less packed.