San Cristobal is one of the oldest geological formations in the Galapagos, and it is closest to mainland Ecuador. The island has unique endemic animals and plants. Certain lava lizards, mockingbirds, giant tortoises, daisies, and prickly pear cacti are only found on this island.

San Cristobal has various native species, including red-footed boobies, frigatebirds, pelicans, boobies, finches, and many different plants and animals.