Riaño Trail Run is a late-June mountain trail event held in Riaño, northern Spain, offering formats from a single stage to a three-stage race. The longest option, Riaño 3xTrail Run, covers up to 84 km with 5,500 m of elevation gain. The two-stage version spans 47.6 km with 3,070 m of climbing. A one-stage option, Riaño Open, begins in Lario and concludes in Riaño.
The full race connects three mountain regions: Fuentes Carrionas y Fuente Cobre-Montaña Palentina, Picos de Europa, and Montañas de Riaño y Mampodre. The three-stage route begins with 36.3 km from Oseja de Sajambre to Caín de Valdeón. It continues with a 21.5 km loop from Valverde de la Sierra, and finishes with 26.2 km from Riaño. Each stage has a time limit. The race operates in a semi-autonomy format, suitable for trail runners who can manage themselves over rugged mountain terrain without constant support.