Lanfonnet, Mountain summit in Alex, France.

Lanfonnet is a mountain ridge in the French Alps near Alex with steep rock walls and an elevation around 1800 meters. The formation consists of limestone and defines the landscape with its sharp vertical structures.

Lanfonnet is the summit of an urgonian limestone cuesta whose north-south cliff face marks the western rim of a perched syncline. The same folding left the Dents de Lanfon as an outlier to the northwest and, opposite, the Roc Lancrenaz and Arête Couturier as the eastern rim. The summit reaches 1,793 m at the northern end of the cliff, while the southern end is the Roche Murraz at 1,768 m.

The name Lanfonnet relates to the Dents de Lanfon, the isolated limestone butte just to the northwest. The mountain's eastern side holds the aulp Riant, an alpine pasture crossed by the GR 96 and the GRP Tour du Lac d'Annecy long-distance paths.

The summit path leaves from the small col between roche Murraz and roc Lancrenaz, at the southern end of the alpage crossed by the GR 96 and the GRP Tour du Lac d'Annecy via the aulp Riant. The final stretch climbs steeply to the 1,793 m crest, so allow time for the return.

From the summit, visitors can see Lake Annecy on clear days and overlook nearby peaks such as Dents de Lanfon. This far-reaching view makes it a favorite spot for mountain photography.