The Guadalquivir is one of six great rivers in . The Guadalquivir is the easiest to navigate and also the deepest of the Spanish rivers. This river which was originally known as Betsi, then as Tarteso and Betis, flows through Jaen, Cordoba, Seville, Huelva and Cadiz. The Miño, Tajo, Guadiana and Duero rivers flow into the Atlantic, passing through while the Ebro passes through the dry landscapes of Zaragoza and flows into the Mediterranean Sea. The Tajo, or Tagus in English, is the longest river in and is navigable for a good part of its course. These rivers provide a good source of electric power in .