The Geltenfall (or Geltenbachfall) is one of the most special waterfalls I ever have seen and is located in the Gasteretal near Kandersteg in the region Berner Oberland, Switzerland.
The Geltenfall is being fed with water from a system of rivers in the mountain Tatelishore. The Geltenbach is part of an underground system of rivers and is called the Geltenbachhöhle. Since the 70s research was done and the years after they discovered that the total length of the tunnels (rivers) in the mountain was 1.3 km with a descend of 50 meter. More information about the Geltenbachhohle can be found here.
The Gasteretal is only accessible through a tunnel with an entrance fee. The road is very narrow that cars only can go oneway through the tunnel. Every 20 minutes you can go through. I read that you have to book a ticket in advance, but the valley is very beautiful as far I can remember. We were visiting the Kandersteg region in May 2005 so it is a long time ago.
Once through the tunnel there are several nice (unnamed) waterfalls you can admire from a distance. The Geltenfall is located at the right side and is one of the first big waterfalls you see. With a total height of 70 meter one of the nicer waterfalls in the region.
As said there are many other waterfalls in the Gasteretal, about five of them are worthwhile to mention. Best is to explore them yourself,
Besides the many waterfalls in the Kandersteg and Kiental region there is also my absolute favorite waterfall that lies in the neighbor valley near Adelboden, the Engstligenfall with a total height of 415 meter.
If you want to see more great waterfall you can drive further to Lenk. There are several other great waterfalls near Lenk but the most famous one is the Simmenfälle. From here you can walk to several other great waterfalls but Siebenbrunnen is a another gorgeous karstic waterfall.