Switzerland - Bätterich, sped up clip from a side tunnel near the drop into the second sump 

The back of the Bätterich holds a few interesting areas. Just before the drop down to 80m there is a bypass tunnel to the right. In that tunnel is a side tunnel going away to the right at app. 18m depth. There is a line in there but its in poor condition as the tunnel is not dived very often. Here a short clip, speed up.