"The largest aquarium in the world", as Jacques-Yves Cousteau nicknamed it, houses an exceptional fauna. The best way to observe it remains scuba diving (for experienced divers) in numerous sites rich in surprises, with dreamy names: Monserrat Island, Coronado Island, Punta Colorada and Bahia Amortajada on San Jose Island, Espíritu Santo Island, Cerralvo Island... 39% of known marine mammal species on Earth, 900 species of fish, and 33 cetacean species thrive here. Great dolphins, gray and blue whales, hammerhead sharks, whale sharks, sea lions, and turtles have been identified in the region.