瓜地亚纳河（Guadiana），又名奥地亚纳河（Odiana），发源于西班牙的卡斯蒂利亚-拉曼恰，向西流经埃斯特雷马杜拉后折向南方，成为西班牙和葡萄牙的一条界河，分隔了西班牙的埃斯特雷马杜拉、安达卢西亚和葡萄牙的阿尔加维、阿尔加维，在西葡两国相邻的两座城市——西班牙的艾阿蒙特和葡萄牙的圣安东尼奥雷阿尔城之间注入加的斯湾。 瓜地亚纳河全长818公里，是伊比利亚半岛第四长的河流；其流域面积则达到了67,733平方公里，在西班牙位居第一。

The Guadiana River (Spanish pronunciation: [ɡwaˈðjana], Portuguese: [ɡwɐðiˈɐ̃nɐ]), or Odiana, is an international river defining a long stretch of the Portugal-Spain border, separating Extremadura and Andalucia (Spain) from Alentejo and Algarve (Portugal). The river's basin extends from the eastern portion of Extremadura to the southern provinces of the Algarve; the river and its tributaries flow from east to west, then south through Portugal to the border towns of Vila Real de Santo António (Portugal) and Ayamonte (Spain), where it flows into the Gulf of Cádiz. With a course that covers a distance of 829 kilometres (515 mi), it is the fourth-longest in the Iberian peninsula, and its hydrological basin extends over an area of approximately 68,000 square kilometres (26,000 sq mi) (the majority of which lies within Spain).