The main valley in the Valais widens, sun warms the dry mountain slopes. Between Leuk and Sierre an unruly part of the Rhone, and the Pfynwald, a nature reserve on a huge mound of glacier detritus; a motorway will be built here.

Between Susten and Sierre lies the Pfynwald, the heart of the Pfyn-Finges Nature Park. A huge pine forest occupies the valley floor through which the wild Rhone flows. The park stretches from the vineyards to the summit of the Weisshorn (4500 m).