The first mountain stage of the Tour departed south-west from Pau, through Lasseube to Oloron-Sainte-Marie. The riders then headed south through Gurmençon to Escot, to begin the climb east to the Category 1 Col de Marie-Blanque to . The route then descended east to the valley floor at Bielle, before beginning a gentle climb south through Laruns and turning east to Eaux-Bonnes. The riders then began the Hors catégorie climb of the Col d'Aubisque to , partially descending through the Col du Soulor, and then climbing the Category 2 Col des Bordères to , before the final big descent to Argelès-Gazost. Heading south, the brief climb of the Category 4 Côte de Saint-Savin was followed by a quick descent to Pierrefitte-Nestalas. The race continued south, beginning the ascent of the Category 1 climb to Le Cambasque, west above Cauterets, at an altitude of .