Doñana National Park is a natural reserve in Andalucía, southern Spain, in the provinces of Huelva, Cádiz and Seville. It covers 543 km², of which 135 km² are a protected area. The park is an area of marshes, shallow streams, and sand dunes in Las Marismas, the delta where the Guadalquivir River flows into the Atlantic Ocean. It was established as a nature reserve in 1969 when the World Wildlife Fund joined with the Spanish government and purchased a section of marshes to protect it. The eco-system has been under constant threat by the draining of the marshes, the use of river water to boost agricultural production by irrigating land along the coast, water pollution by upriver mining, and the expansion of tourist facilities. It is named after Doña Ana de Silva y Mendoza, wife of the 7th Duke of Medina Sidonia.
Doñana National Park has a biodiversity that is unique in Europe, although there are some similarities to the Parc Naturel Régional de Camargue of the Camargue river delta in France, with which Doñana Park is twinned.