Geologically, San Cristobal Island is one of the oldest islands in the Galápagos archipelago. It is home to the only source of fresh water in the islands, a small lake called Laguna El Junco. The lake hosts a large population of birdlife, as does the rest of the island. Other animal inhabitants include sea lions, tortoises, marine iguanas, dolphins, lobsters and more. One of San Cristobal Island's most popular visitor sites is Cerro Brujo, with its expansive white sand beach and a lagoon that locals once used as a salt mine but now offers excellent snorkeling opportunities. Another must-see is Kicker Rock, a fascinating rock formation that looks like a boot from one angle (hence its English name) and like a sleeping lion from another (thus its Spanish name, Roca León Dormido).