The Grimselsee is an artificial lake with a surface area of 2.63 km2, located in the Halistal Valley, rich in crystal stones. Near the Grimselsee there is a unique crystal cave at Gerstenegg is approximately 1.5 km inside the Grimsel massif and is the only accessible cave in the Alps in its original form, an impressive wonder of nature. With an impressively rugged and sparse alpine landscape, interspersed with glaciers, reservoirs and hydroelectric plants near the Grimsel Pass in Canton Bern, Switzerland.