Montes Obarenes-San Zadornil Natural Park, Nature reserve in Burgos, Spain

Parque Natural Montes Obarenes-San Zadornil is a protected area between the Cantabrian Mountains and the Ebro Valley with deep gorges, dense forests, and limestone cliffs. The terrain features mountain ridges with streams and natural rock walls that create a complex landscape.

The park lies in northeastern Burgos, on the border with Álava. The mountains form the southernmost foothills of the Cantabrian range, rising above La Bureba. Castilla y León proposed the area as a Site of Community Importance on 18 March 1999, and the EU designated it a Special Protection Area for Birds on 31 August 2000. It was declared a natural park in 2006, covering 33,064 hectares across 53 villages.

The park takes in the towns of Oña, with its San Salvador monastery, and Frías, with its castle, hanging houses and Roman bridge. Valpuesta, within the Jurisdicción de San Zadornil, lies inside the protected area. The park covers 53 villages with 6,806 inhabitants.

Visitor centers in Oña and San Zadornil provide information and orientation for exploring the area. More than 20 marked trails of varying difficulty are available, so both casual walkers and experienced hikers can find suitable routes.

The reserve shelters European mink and native crayfish, species that have become rare elsewhere. These animals thrive in the cool streams and woodland zones where they find protection from disturbance.