Klass7
Sumgait Kutukov Cave (Pit) is the longest cave in the Ural Mountains.   The entrance is a 110 meter pit.  It is only accessible to experienced cave explorers with advanced vertical equipment and training.   The cave has be mapped to 9860 meters of length.   However the lowest level of the cave has been flooded. (OSM data version: 2016-12-14T16:41:03Z) #mapsme