The Guadiana River (Spaingie pronunciation: [ɡwaˈðjana], Portuguese: [ɡwɐðiˈɐ̃nɐ]), or Odiana, is an internaitional river defining a long stretch o the Portugal-Spain border, separatin Extremadura an Andalucia (Spain) frae Alentejo an Algarve (Portugal). The river's basin extends frae the eastren portion o Extremadura tae the soothren provinces o the Algarve; the river an its tributaries flaw frae east tae wast, then sooth throu Portugal tae the border touns o Vila Real de Santo António (Portugal) an Ayamonte (Spain), whaur it flaws intae the Gulf o Cádiz. Wi a coorse that covers a distance o 829 kilometre (515 mi), it is the fowert-langest in the Iberian peninsula, an its hydrological basin extends ower an area o approximately 68,000 square kilometre (26,000 sq mi) (the majority o which lies within Spain).

Guadiana River
Rio Guadiana
Guadiana river.jpg
The River Guadiana in the aurie aroond Serpa, Portugal
Name oreegin: Arabic derivative o Wadi Ana, meanin River Ana
Kintras Portugal, Spain
 - left
 - right
Soorce Ojos del Guadiana
 - location Villarrubia de los Ojos, Castile–La Mancha, Spain
 - elevation 608 m (1,995 ft)
 - coordinates 39°7′36″N 3°43′36″W / 39.12667°N 3.72667°W / 39.12667; -3.72667
Mooth Gulf of Cádiz
 - location Vila Real de Santo António, Algarve, Portugal
 - elevation 0 m (0 ft)
 - coordinates 37°10′12″N 7°23′37″W / 37.17000°N 7.39361°W / 37.17000; -7.39361Coordinates: 37°10′12″N 7°23′37″W / 37.17000°N 7.39361°W / 37.17000; -7.39361
Lenth 818 km (508 mi)
Depth 17 m (56 ft)
Basin 67,733 km2 (26,152 sq mi)
 - average 600 m3/s (21,189 cu ft/s)
 - max 1,500 m3/s (52,972 cu ft/s)
 - min 20 m3/s (706 cu ft/s)
Rio guadiana.svg
Aboot 83 percent, 55,000 square kilometre (21,000 sq mi), o the River Guadiana wattershed is in Spain; the rest is in Portugal