The Maratón de las Tucas is a 42-kilometer mountain marathon held in Benasque, within the Spanish Pyrenees, as part of the Gran Trail Aneto Posets. Taking place in July among six events, it features 2,500 meters of elevation gain, establishing it as a genuine trail marathon distinct from a road race with inclines. The start line is located on Avenida de los Tilos, and the event attracts approximately one thousand participants, making it the most popular race within the Gran Trail Aneto Posets series.
The course encircles the Tucas de Ixeia, a cluster of peaks reaching 2,840 meters above the valley. It also crosses the Batisielles lakes, the Espigantosa waterfall, and the hamlets of Anciles and Cerler. The field comprises elite mountain runners alongside a substantial number of participants; Pablo Bautista and Leire Fernandez are past winners, with Bautista also holding the course record. Damp terrain following nocturnal rainfall can increase the technical difficulty of the already steep course.