The main city beach runs along the northern edge of the centre, easily walkable from the casino, the flower clock, and Wulff Castle. It is wide, sandy, and well-maintained, with the city's coastal avenue (Avenida Marina) running behind it. The beach serves a mixed crowd — families, couples, and anyone who wants the beach without the full Reñaca scene — and it is the most convenient option if you are staying in the city centre.
The esplanade behind the beach is good for an evening walk regardless of whether you swim: palm trees, ice cream vendors, the castle on its promontory, the Pacific light doing what it does at the end of the day. In summer the beach fills by midday; in winter you may have long stretches to yourself, which is its own reward.