Gran Trail Peñalara 104K

The Gran Trail Peñalara 104K is the flagship race of Spain's most storied mountain ultramarathon. Starting and finishing in Navacerrada under the stars at 23:30, the course circumnavigates the Sierra de Guadarrama in a 104km loop through the heart of a national park. Runners climb past La Maliciosa, descend into the Lozoya valley at Rascafría, ascend to the 2,428m summit of Peñalara, and return via La Granja and Guarramillas — accumulating 5,100m of vertical gain across mountain singletrack, forest roads, and brief stretches of tarmac. Held since 2010 and recognized as a UTMB 100K Index race awarding 6 ITRA points, the GTP is a cornerstone of Spanish ultra trail culture.