Between January and March, grey whales migrate through the Sea of Cortez on their way south to the breeding lagoons of Baja California Sur. The passage brings them close enough to shore that whale-watching trips from the San Carlos marina are reliably productive. Blue whales — the largest animals on earth — also appear in the central Sea of Cortez during winter and can occasionally be seen on longer offshore excursions.
Several local operators run three- to four-hour whale-watching tours by panga or larger vessel. The combination of calm winter weather and the whales' proximity to the coast makes this one of the more accessible whale-watching experiences in Mexico. Humpbacks and fin whales are additional possibilities, particularly in deeper water.