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. It’s a series of ten glacier-fed waterfalls inside the mountain made accessible by a tunnel-funicular, built 1913. You can choose to take the stairs too. The funicular takes you up to the 6th floor (out of 10). This attraction is truly impressive, a gift of nature and a must do when visiting the area. Kids under 4 years old are not allowed.
https://goo.gl/maps/r25oAYoDgnfzXqzm8
https://www.truemmelbachfaelle.ch/e/