on the western side of the Nicoya Peninsula, this
refuge has 162 hectares of land areas and 587 hectares
in the sea.
The very large Ostional Beach, together with Nancite
Beach in the Santa Rosa National Park, is the most
important nesting site for the olive ridley (Lepidochelys
olivacea) on Earth. The refuge includes a large
mangrove swamp at the mouth of the Nosara River. Over
100 birds have been identified in the area.