El Junco Lagoon, the only freshwater lake in the Galapagos archipelago, is located in the highlands of San Cristobal. The lake is situated inside a small crater which in turn is located within the caldera of an extinct volcano. This site is a popular place for frigate birds that like to swoop down into the lake to bathe and wash their wings. During the dry season its depth can decrease to six feet, while the lake can overflow during the rainy season from January to February, forming small streams flowing down the side of the mountain.