Oca (river)

Oca
Latin: Vesica
Watershed of the Oca at Villalbos (Valle de Oca)
Country	Spain
Tributaries
- left	Cerratón, Anguilas, Homino
- right	Matapán
Source	Montes de Oca
- location	Rábanos, Montes de Oca, Burgos, Castile and León, Spain
- elevation	1,186 m (3,891 ft)
Mouth	Horadada Gorge, Ebro river
- location	Oña, La Bureba, Burgos, Castile and León, Spain
- elevation	570 m (1,870 ft)
- coordinates	42°46′02″N 3°25′59″W / 42.767213°N 3.433021°W / 42.767213; -3.433021Coordinates: 42°46′02″N 3°25′59″W / 42.767213°N 3.433021°W / 42.767213; -3.433021
Length	70 km (43 mi)
Oca river is the first Ebro tributary river on the right bank
Location of the mouth with Castile and León Show map of Castile and León Location of the mouth with Castile and León Show map of Spain

The Oca river is a short river, about 70 kilometres (43 mi) long, in the north of Spain. It is an affluent of the Ebro river that flows through the province of Burgos. It begins in the Sistema Ibérico range and flows north through the municipalities of Rábanos, Villafranca Montes de Oca, Valle de Oca, Alcocero de Mola, Prádanos de Bureba, Briviesca, Vileña, the shire of Bureba and Oña.

The Oca River rises in the comarca of Montes de Oca, near the town of Rábanos. Near its source, the river passes through the narrow, rock-lined gorge of La Hoz. This passage, 700 metres (2,300 ft) long and 100 metres (330 ft) high, was of great strategic value in the 11th century and was defended by the castle of Alba.

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