* The Ebro River is the longest river in Spain, flowing 930 km through the regions of Cantabria, Castile and León, La Rioja, Navarre, Aragon, and Catalonia.
* The Duero River is the second longest river in Spain, flowing 897 km through the regions of Castile and León, and Portugal.
* The Tagus River is the third longest river in Spain, flowing 1007 km through the regions of Aragon, Castile-La Mancha, Extremadura, and Portugal.
* The Guadiana River is the fourth longest river in Spain, flowing 744 km through the regions of Castile-La Mancha, Extremadura, and Andalusia.
* The Guadalquivir River is the fifth longest river in Spain, flowing 657 km through the regions of Andalusia.