La Grande Sure, Mountain summit in Chartreuse, France.

La Grande Sure is a limestone mountain peak in the Chartreuse range of the French Alps, located in the Isère department, rising to 1,920 meters (about 6,300 feet). Its slopes are steep and rocky on all sides, and its outline is visible from much of the surrounding massif.

The pastures of the Grande Vache and the Petite Vache valley appear on the Cassini map, and the Rochers de la Sure are first named on 18th-century état-major maps, at 1,924 m. Antonin Macé, a Breton who became professor of history at Grenoble, mentioned the Grande Sure in 1860. The summit cross and its stone cairn stand on the ridge today.

La Grande Sure is a familiar reference point for hikers crossing the Chartreuse range, drawing people who want to walk through open limestone terrain with wide views. The paths leading to the top are part of a well-used network that connects villages across the area.

The peak can be reached from the eastern side by a less demanding route, or from the western side by a path that calls for more technical experience. Solid footwear is needed throughout because the ground is rocky, and checking weather conditions before setting out is a good idea at this elevation.

The summit ridge shows traces of an old erosion surface, a peneplain formed around the end of the Pliocene while Alpine folding was still under way. The summit itself is Fontanil limestone, a Valanginian marine deposit from the Lower Cretaceous, whereas the Urgonian limestone typical of other Chartreuse peaks appears only on the eastern side of the Hurtières ridge.