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.

Due to its strategic location between the continents of Europe and Africa and its proximity to the Strait of Gibraltar, Doñana's large expanse of salt marsh is a breeding ground as well as a transit point for thousands of European and African birds (aquatic and terrestrial), and hosts many species of migratory waterfowl during the winter, typically up to 200,000 individuals.

Considered the largest nature reserve in Europe, several different scientific institutions have monitoring stations within its boundaries to ensure appropriate development of adjacent lands and conservation of the threatened species that inhabit it.

The geological profile of Doñana National Park reflects the development over several hundred thousand years of a deep aquifer and geomorphological features that have enhanced the biodiversity of the wildlife habitats presently found there.

After the end of the last glacial period, the area was covered by freshwater and brackish marshes, ponds and sand dunes,[6] with some marine intrusions caused by high-energy events such as tsunamis and large storms.

The extensive marshes of Doñana National Park now have a flat topography, with some inland depressions occupied by temporary or permanent wetlands, locally called 'lucios'.

Various ancient civilizations may have had a presence there as long as 2,800 years ago, including the Phoenicians, the Phocaean Greeks and the Tartessians, but archaeological remains attesting to such have not been found.

In 1297, his son Sancho IV granted Guzmán el Bueno the Lordship of Sanlúcar, consisting of the territory located behind Arenas Gordas on the left bank of the Guadalquivir estuary, and which remained in the hands of the House of Medina-Sidonia for over six centuries.

[19] In 1493 the Catholic Monarchs donated part of the land of the present village of El Rocío to the royal secretary, whose son later sold it to the town of Almonte.

Previously, new breeding stock had been introduced among the local populations of wild boar and deer, while wolf hunting was encouraged for the benefit of cattle and horse ranching.

In the region of Niebla, specifically at Las Rocinas, the land is flat, covered by thickets, and wild boars are always to be found there... ...one may not traverse this ground in the winter, which is generally very wet, except during a drought, nor in summer because it is then so dry and miserably uncomfortable.

Consequently, it was visited by British naturalists and hunters including Abel Chapman and Walter J. Buck, both of whom wrote books that alerted a wider audience in Europe to the strategic importance of Doñana for migratory birds traveling to Africa.

The Spanish businessman Mauricio González-Gordon y Díez, Marquis of Bonanza, whose family owned a large estate in Doñana, became interested in its ecosystems and their birdlife, and invited ornithologists from all over Europe to visit.

Valverde and the González-Gordon family saw that the wetlands, with their richly diverse wildlife, were threatened by the Spanish government's proposals to drain them for farming and the planting of eucalyptus trees.

[23] Valverde led the first organised scientific expedition to the Donana in 1957, joined by the British naturalists Guy Mountfort, Roger Peterson, and Sir Julian Huxley.

Valverde, Hoffman, and Nicholson, in partnership with the British Nature Conservancy, formed an association that organised an international drive for funds to expand the park.

WWF still supports the Doñana, and is fighting proposals to drain the marshes and syphon off water for irrigation of agricultural land along the coast and expansion of tourist facilities.

In 1998, the Aznalcóllar Disaster occurred when a holding dam burst at the Los Frailes mine owned by Boliden-Apirsa (formerly Andaluza de Piritas, S.A.), the Spanish subsidiary of Boliden, releasing a flood of toxic sludge that entered the River Guadiamar, the main water source for the park.

[29] The court ruled in favor of the EU commission, stating that Spain has not fulfilled its obligations concerning the prevention of illegal water extraction as well as failed to take necessary measures to stop significant modifications of the park's landscape.

Doñana Park has a mild, typically Mediterranean climate, characterized by dry summers and relatively wet winters resulting from variations in the polar front and the subtropical ridge of high pressure.

Of special interest are the species Vulpia fontquerana, Tursica linaria, Juniperus macrocarpa (maritime juniper), Micropyropsis tuberosa, Hydrocharis morsus-ranae or Thorella verticillatinundata, many of them endangered.

Non-native species such as eucalyptus, Acacia longifolia, Gomphocarpus fruticosus, Nicotiana glauca or Carpobrotus edulis (cat's claw) are removed by the park service.

The gradual burial of vegetation, especially of trees that emerge then die, killed by the slow movement of sand, is one of the most well-known phenomena in the beach area of the park.

Native fish such as eel inhabit Doñana as well as introduced species such as carp, and the gambusia, or pike, which is considered an invasive threat to local ecosystems.

Wetland species include glossy ibis, western swamphen, ferruginous duck, Eurasian spoonbill, red-crested pochard, little and cattle egret, night and squacco heron and greater flamingo, whilst the surrounding areas can have hoopoe, stone-curlew, Spanish sparrow, Mediterranean short-toed lark and pin-tailed sandgrouse.

These conservation efforts are threatened by a high mortality rate among the cats and recurring violations of laws prohibiting cars from entering the park or driving on its roads, although, as some agencies have reported, the causes of death are not always clear.

Another environmental problem is water withdrawals for irrigation, many of them illegal, which have doubled since the late 1980s to maintain water-intensive crops such as cotton, rice and more recently strawberries.

To ensure sustainable development both in the countryside and in the surrounding provinces, as well as to counteract future environmental threats, an International Commission of Experts met in 1992 to propose solutions, and produced the Plan de Desarrollo Sostenible de Doñana y su Entorno (Plan for Sustainable Development of Doñana and its Surroundings), briefly described as: A plan of action, implemented through the Doñana Operational Programme and funded by the regional government of Andalusia and the Spanish State, as well as the Feder Funds, ESF and EAGGF, to revitalise both the regional infrastructure and social fabric through a new economic model of development compatible with preserving the biodiversity of such an extraordinarily important natural heritage as Doñana.This effectively became the mission statement of the Doñana 21 Foundation, created in 1997 as a partnership between the Governing Council of the Andalusian Regional Government and the El Monte, San Fernando and Unicaja savings banks.

The popularity of the cult of the Virgen del Rocío in modern times has raised concerns about the annual pilgrimage's effect on the natural environment of the park.

[27] Another important activity of longstanding association with the park is La Saca de las Yeguas [es] ("The Gathering of the Mares"), a livestock event from Almonte pertaining to the indigenous wild horses of the salt marshes of Doñana.