Heading back up the Gressoney Valley, in the municipality of Fontainemore, roughly 14 km from the Bard Fortress, you will find a haven of wild, pristine nature just waiting to be explored: this is the Mont Mars Nature Reserve, stretching over an area of 390 hectares on the left-hand bank, when looking downstream, of the lower Lys Valley, at the jaws of the deep narrow valley formed by the Pacoulla stream.

At the entrance to the protected area you will find the charming Lake Vargno. The nature reserve stretches between altitudes of 1670 m and 2600 m, featuring a variety of typically Alpine environments of considerable importance: forests interspersed with pastures and Alpine grasslands, from screes to rock faces, lakes and wetlands. In the lower part and around the lakes, there are also a few Alpine pastures, most of which are still in use today.

The highest peak, which towers over the area with its majestic pyramid, is Mont Mars itself. Standing 2600 m high, it soars above a dry landscape of screes and sheer rock faces. The basins with the many little lakes alternate, in the upper part, with the rocky crags formed by roches moutonnées, or sheepback rocks: rocks polished by the erosive action of glaciers. There is plenty of wildlife here, consisting mainly of Alpine marmots, chamois, black grouse, hares and snow-grouse.