Elevation: 1,944m. For 10km, you travel through the charming Lesponne Valley, from which the striking rocky faces of the Pic du Midi de Bigorre and the Pic de Montaigu come into view. The road ends at the Chiroulet car park, the starting point of the hike: a long climb along a well-marked path leads to this grandiose site. The last ascent before you see the Lac Bleu is a bit difficult but worth the effort. Located in a verdant setting, the lake owes its name to its beautiful blue waters, even if some argue they are green!