The Oca river is a short river, about 70 km, of the north of Spain, It is an affluent of the Ebro

Ebro

The Ebro or Ebre is one of the most important rivers in the Iberian Peninsula. It is the biggest river by discharge volume in Spain.The Ebro flows through the following cities:*Reinosa in Cantabria.*Miranda de Ebro in Castile and León....

 river that flows through the province of Burgos. It is born in the Sistema Ibérico

Sistema Ibérico

The Sistema Ibérico or Iberian System is one of the main systems of mountain ranges in Spain.It is a vast and complex system of mountain chains and massifs located in the central regions of the Iberian Peninsula, but reaching almost the Mediterranean coast in the Land of Valencia in the east.From...

 range and it has 70 km of route, crossing of the south to north the municipalities of Rábanos

Rábanos

Rábanos is a town of northern Spain, Autonomous Community of Castile and León, province of Burgos, Shire of Montes de Oca, sub-shire of Tirón-Rioja Burgalesa, it is the head of the municipality of Rábanos....

, Villafranca Montes de Oca

Villafranca Montes de Oca

Villafranca Montes de Oca is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2005 census , the municipality has a population of 164 inhabitants....

, Valle de Oca

Valle de Oca

Valle de Oca is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2004 census , the municipality has a population of 226 inhabitants....

, Alcocero de Mola

Alcocero de Mola

Alcocero de Mola is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2004 census , the municipality has a population of 53 inhabitants....

, Prádanos de Bureba

Prádanos de Bureba

Prádanos de Bureba is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2004 census , the municipality has a population of 59 inhabitants....

, Briviesca

Briviesca

Briviesca is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2007 census , the municipality has a population of 7,227 inhabitants....

, Vileña

Vileña

Vileña is a municipality located in the province of Burgos, Castile and León, Spain. According to the 2004 census , the municipality has a population of 31....

, the shire of Bureba and Oña.

Oca River rises in the shire of Montes de Oca, near Rábanos

Rábanos

Rábanos is a town of northern Spain, Autonomous Community of Castile and León, province of Burgos, Shire of Montes de Oca, sub-shire of Tirón-Rioja Burgalesa, it is the head of the municipality of Rábanos....

. Within walking distance of their current source follows the narrow gorge of La Hoz of 700 meters long and 100 high of sheer rocks, Passage of great strategic value, in the eleventh century, defended by the castle of Alba.

Affluents

On the right receives the waters of the river Matapán and the streams Valsorda and Penches, while on the left receives the waters of the rivers Cerratón, Anguilas and Homino, and the streams Valdazo and Hoyo.