The Odra is a

river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...

Spain , image_flag = Bandera de España.svg , image_coat = Escudo de España (mazonado).svg , national_motto = ''Plus ultra'' (Latin)(English: "Further Beyond") , national_anthem = (English: "Royal March") , i ...

. Its springs are located to the north of Amaya mountain in the

province of Burgos The Province of Burgos is a province of northern Spain, in the northeastern part of the autonomous community of Castile and León. It is bordered by the provinces of Palencia, Cantabria, Vizcaya, Álava, La Rioja, Soria, Segovia, and Valladolid. ...

, from where it flows southward until reaching the

Pisuerga River The Pisuerga is a river in northern Spain, the Douro, Duero's second largest tributary. It rises in the Cantabrian Mountains in the province of Palencia, autonomous region of Castile and León. Its traditional source is called Fuente Cobre, but i ...

. The main

tributary A tributary, or affluent, is a stream or river that flows into a larger stream or main stem (or parent) river or a lake. A tributary does not flow directly into a sea or ocean. Tributaries and the main stem river drain the surrounding drainage ...

is the Brullés River.

See also