Jacques Cousteau famously called the Sea of Cortez the “Aquarium of the World,” and when we run shop trips from Tucson down to San Carlos, we get to see why. But the Gulf of California is a vast, dynamic ecosystem, and a lot of divers arrive with unrealistic expectations (or no idea what to look for). Will you see a whale shark? Maybe. Will you see a seahorse? Only if you have a great guide. Here is your realistic field guide to the incredible marine life you can actually expect to encounter on your next San Carlos adventure.