The Híjar rises on the southern slope of the Cordillera Cantábrica and falls through the Campoo country to feed the Embalse del Ebro. A different Cantabrian river to the Atlantic-flowing systems — drier landscape, Mediterranean side of the divide, mixed limestone-and-sandstone geology. Wild brown trout only. The middle reaches around Reinosa and Entrambasaguas hold the most fishable water, with classic pool-riffle structure and partial canopy. Best fished from late April through June; the river drops away quickly in the dry Castilian summer.
- Mixed
