Loud thundering and roaring in the interior of the mountain, gurgling, foaming and churning water: these are the Trümmelbach Falls. They are Europe's largest subterranean water falls and are located in the Lauterbrunnen Valley, often called the valley of 72 waterfalls.
The Tümrmelbach Falls are the world's only glacier waterfalls that are accessible underground by lift, galleries, tunnels, paths and platforms. They alone carry the meltwater of the glaciers from the Jungfrau down to the valley - up to 20,000 liters of water per second. The water carries with it over 20,000 tons of boulders and scree per year and causes the entire mountain to shudder and make a thundering noise.
The Trümmelbach Falls are part of the Lauterbrunnen Valley's 72 waterfalls, among them also the imposing Staubbach Falls. The hiking tour on mainly flat land leads from Lauterbrunnen to Stechelberg, past water gushing from vertical rock faces that are several hundred meters high.
One can incorporate this with visits to Piz Gloria (Schilthorn) which is very close. To visit there, I stayed at Alpenblick campsite near Interlaken : http://www.motorhomefulltime.com/campsite/alpenblick-unterseen-switzerla...