It is not the length of a single route but the aggregate of passages distributed across the upper three levels of the cave system.

Different passages at different distances from the entrance, all showing evidence of people who came with bundles of lit cane and mussel shells and gourd bowls and rope and climbing poles.

The passages range from relatively near the entrance — the first few hundred meters where early exploration and surface shelter use have been documented — to distances that, by the time researchers from Western Kentucky University and the Cave Research Foundation mapped and analyzed them, required hours of underground travel to reach.

Some of the mineral-bearing walls showing mining evidence are at distances that, under the flickering light of a cane torch, would represent many hours of underground navigation.