The Grande Trail da Serra D'Arga takes place in late September in the District of Viana do Castelo, offering trail races from 15 km to 100 km. This event is a mountain and forest running weekend, not a single-distance race, with courses included in the UTMB World Series circuit. The available distances are 15 km, 17 km, 31 km, 50 km, and 100 km, allowing participants to select anything from a shorter trail run to a full ultra.
Each distance is designed as a single loop, guiding runners through protected natural areas, woodlands, and rugged trails surrounding Serra d'Arga. The 50 km race provides a good indication of the terrain: 50.00 km with 3,000 meters of elevation gain, sufficient for a challenging mountain day. The 15 km, 17 km, 31 km, and 50 km races award UTMB Index points, attracting both aspiring beginners and seasoned ultra-trail runners.