Douro

The Douro is one of Spain's major rivers and the Iberian Peninsula's third longest. It flows across Spain and Portugal, with a total distance of 557 kilometers. Its origins can be found in central Spain's Sierra de Urbión. It flows through the Numantian Plateau before flowing westward into northern Portugal and into the Atlantic Ocean. The Elsa, Arlanzón, and Pisuerga are the three primary tributaries of the Douro.

Since 1930, the river has been used to generate hydroelectric power. Olive and almond trees are grown in the river basin. The Douro Valley is a UNESCO World Heritage Site known for its wines. In the past, the river was used to convey wine from the vineyards. The river runs through gorges and rapids upstream, making navigation difficult, however it is passable downstream in Portugal. Along the banks of the Douro, many Spanish and Portuguese cities have been developed.

Length: 557 miles (shared with Portugal)