Tags: Cave.
The Hölloch is a 200.4 kilometres (124.5 mi) long cave in the Muotathal municipality in Switzerland. It is also notable for having a depth of 938.6 metres (3079 ft) and being the second longest cave in Europe. The initial exploration started in 1875 and was led by Alois Ulrich. A large part of the exploration of this cave was led by one of the pioneers of speleology Alfred Bögli.
