It’s worth the trek (and metered traffic) to reach Europe's largest alpine lake, Lac d’Allos (2226m; inaccessible fall to spring). From Allos, narrow, bumpy D226 climbs 12km to parking; then it's a 40-minute walk. Trail maps are available from the summer-only Parc National du Mercantour hut at the car park. Sited right beside the lake, the Refuge du Lac d'Allos is an ideal spot for lunch, and has dorms if you're planning an overnight hike.
Parc National du Mercantour