San José's beaches line the Sea of Cortez coast south and east of town. The strong shore break along most of the beach in front of the hotels makes swimming unsafe — the water is beautiful to look at but deceptive — and the calmest water is at Playa Palmilla, a small sheltered cove 15 minutes south of town with clear water and good snorkelling.
Playa Costa Azul, directly south of town, is the best surf beach in the Los Cabos area, with a consistent reef break that handles swells from the south Pacific. A surf camp operates at the beach. La Playita (The Little Beach), east of town near the estuary, is a working fishing beach where sport fishing boats depart and the fishermen sell their catch directly off the boats in the morning. Swimming is not advised but the atmosphere is genuinely local.
For protected swimming outside Palmilla, the best options are beaches further up the corridor toward Cabo San Lucas — Playa Chileno and Playa Santa Maria both have calm, clear water with offshore reefs.