The Douro River is one of the major rivers in the Iberian Peninsula, flowing through Spain and Portugal. It stretches approximately 897 kilometers (557 miles) and is known for its stunning landscapes, including steep terraced vineyards that produce the famous Port wine. The river's source is in the Sierra de Urbión mountains in Spain, and it eventually empties into the Atlantic Ocean near the city of Porto. The Douro Valley, through which the river flows, is a UNESCO World Heritage site recognized for its cultural significance and natural beauty. The river is also vital for transportation and irrigation, supporting local agriculture and tourism. Its scenic cruises attract visitors who wish to experience the picturesque views and rich history of the region.