There are at least 32 rivers and 16 streams that originate close to the Rincón de la Vieja volcano and flow into the Tempisque River watershed. As part of the Zapandí Riverine Wetlands reserve, this watershed is of great ecological and agricultural value, providing habitat for aquatic organisms and a source of irrigation for farming land. Other aquatic and semi-aquatic areas that the Guanacaste Conservation Area span are open marine zones, marine islands, many of which are uninhabited, rocky coasts, dune systems, and beaches, including of sea turtle nesting grounds.