We have done the Black Abyss tour (most expensive ...

We have done the Black Abyss tour (most expensive one). It was definitely worth every single dollar. It was a once in lifetime experience with the fantastic guides Philipp and Harry.
We highly recommend it to all crazy adventurers out there. Floating through the tunnel with thousands of glow worms on the ceiling was one of the most amazing experience we have made. It is like diving into another dimension.