Past its corbelled entrance passages and through a tight lintelled creepway barely half a metre wide, the man-made stonework eventually gives way to something far older, a natural limestone cave roughly five and a half metres by six, where a colony of lesser horseshoe bats, Rhinolophus hipposideros, now roosts in the dark.

The souterrain itself begins within the north hut of what appears to have been a settlement, though its original entrance in the northwest internal wall-face is now blocked. Access into the underground system was, at some point, forced by removing roofing slabs roughly three metres to the northwest. From there, the first passage runs for nearly ten metres, narrow and low, its walls slightly corbelled, meaning they lean inward toward the roof in a technique that distributes weight without mortar. The floor level has been raised considerably by collapse over the centuries. The passage turns westward and eventually leads through a creepway, one side of which is formed by a single thick upright slab, into a further corridor with a possible air vent cut into its southern wall. Where this second passage broadens at its western end, the drystone construction stops and the natural cave begins. Beyond the main cave chamber, a narrow rock-cut passage extends two and a half metres further west into a small rectangular chamber, also apparently of natural origin, though an accumulation of earth blocks any further progress.

What adds an unsettling dimension to this already layered site is the presence of human remains. Bones identified as those of an adult aged at least thirty years were removed from the cave floor in 1991 and examined by researchers at University College Cork. A separate find of bones, also believed to be human, was made in 1953 and sent to England for inspection by the Office of Public Works. Whether these individuals ended up in the cave deliberately, incidentally, or in circumstances now entirely beyond recovery, nobody has established.