San Carlos has several beaches within easy reach, each with a different character. The common features are clean sand, clear calm water, and a desert backdrop. The beaches are not crowded by Mexican resort standards — this is a quiet town, not a Cancún.
Playa Los Algodones is the most celebrated beach in the area, a long arc of pale sand at the east end of town, with Cerro Tetakawi rising directly behind it. The water is calm and the setting is dramatic. Named for the white cotton-ball dunes that used to lie at its southern end, it is the beach most photographers reach for when illustrating San Carlos. This was also the stretch used as a backdrop in the Catch-22 shoot.
Playa San Francisco is the central, most accessible beach, close to most of the restaurants and the marina. It faces west, which means reliable sunsets with Tetakawi silhouetted against the sky. Good for swimming and kayaking.
Playa Piedras Pintas sits at the base of Tetakawi and is the best beach for snorkelling directly from shore, with rocky outcrops just offshore that hold fish and the occasional ray. No palapas or services, which keeps the crowds thin.
The water temperature in summer reaches 28–30°C, warm enough to swim without a wetsuit. In winter it drops to around 18°C — comfortable for snorkelling with a thin wetsuit.