Ever wondered what a high-mountain lake looks like before the hikers arrive? At over 1,940 metres above sea level, Lake Gentau sits quietly in the Pyrenees of south-west France, its cold waters reflecting granite slopes and shifting clouds. Reached on foot from the Ossau Valley, the lake has long been a pause point for shepherds and walkers crossing these summer pastures. Look up and you will spot the dark volcanic shape of Pic du Midi d'Ossau nearby. Why does that peak matter? For centuries it served as a natural landmark guiding travellers through the mountain passes between France and Spain. Today it sits near the western boundary of the Pyrenees National Park. On calm days the surface turns mirror-still, reflecting sky, rock and the sharp outline of the Ossau peak. Not a bad reward for a mountain walk.