La Paz offers some of the best diving in the Sea of Cortez: More than 25 dive sites surround the islands outside La Paz's bay, such as Espíritu Santo, San José, and Cerralvo. What sets La Paz diving apart is the big stuff: sea lions, rays and sharks like whale sharks and hammerhead. Scuba diving conditions are best from September through November, when visibility is excellent and the water is warm. (Winter water is cold, sometimes down to 20°c or colder, and changing temperatures can mean poor visibility in spring.) Certified divers will get the most out of La Paz's amazing dive sites, including the sea lion colony at Los Islotes, distant Cerralvo Island, the sunken ship Salvatierra, wall dive, and several sea mounts (underwater mountains) and reefs.