This is the souterrain at the heart of a large early medieval cashel, a type of stone-walled ringfort, that does not appear on Ordnance Survey maps and sits in a state of considerable neglect about 370 metres south-south-west of Dunkerron Castle. The cashel measures roughly 64.5 metres in internal diameter, D-shaped in plan, with a low limestone cliff, averaging 2.3 metres high, defining its southern and south-western boundary in place of a built wall. Whether that wall ever ran along the cliff's upper edge is no longer possible to determine.

The site has suffered steadily over recent decades. A trackway constructed in the 1960s cuts north to south directly through it, and land improvement works on its western side levelled the enclosing wall in that area entirely. What remains of the wall survives as a band of stone collapse, 4.5 metres wide and only 0.4 metres high, flush with the surrounding ground. Much of its facing of large flat slabs was removed in the early 1990s. Inside the enclosure, two possibly conjoined stone huts sit close to the trackway; the southern one is now little more than a circular depression about five metres across, while the northern preserves traces of drystone facing and walls up to 2.7 metres wide. The souterrain, a type of underground stone-lined passage associated with early medieval settlement, runs from the north-western wall of the northern hut, extending nearly ten metres before turning west and eventually connecting, through that narrow creepway, to the natural cave beyond. Surveyed passages total well over fifteen metres in length, and a possible air vent is visible along one southern wall.

The cave itself, irregularly shaped and roughly five and a half by six metres, has an uneven bedrock floor sloping to the south-east and averages about a metre in height throughout. Human bones recovered from its floor in 1953 were sent to England for inspection by the OPW; further bones identified in 1991 by C. Power of University College Cork were those of an adult aged at least thirty years. A narrow rock-cut passage at the cave's western end leads to a small rectangular chamber, apparently also natural, though an accumulation of earth now prevents anyone from entering it.