If brooks and rivers run only sluggishly above ground, hydropower is nearly impossible to harness. That is why the inhabitants of the valley of Le Locle began to use subterranean streams. This is how the cave mills of "Col-des-Roches" arose.
Europe's largest subterranean lake that can be sailed upon lies between Sion and Sierre. The water grotto is easily accessible and there is a boat tour for viewing it. The guides on the boat tell visitors about the history of the cave and its geology.
Already Neanderthal men were here where today a cableway sweeps visitors up and over the rugged rocks of the once populated Ebenalp caves - and a great departure point for various discoveries.
For centuries the ownership of salt mines meant wealth and power. The salt deposits at Bex, discovered in the 15th century, are still mined today. The salt mines are accessible to visitors, a museum depicts the mining of salt from 1684 to the present.