The uncertainty is part of the point. A souterrain is an underground stone-lined passage, typically built during the early medieval period and associated with nearby settlements or ringforts, used variously for storage, refuge, or purposes still debated by archaeologists. This particular example leaves almost nothing to see. There is no visible surface trace, and the only recorded opening was described as barely eighteen inches across, so slight that the antiquarian who examined it thought it looked less like a man-made entrance than the burrow of a fox or a badger.

That description comes from T. J. Westropp, writing in 1915, who recorded the feature in the north-east quadrant of a cliff-edge fort at Dunkelly. Cliff-edge forts are a distinctive class of coastal promontory enclosure found along the Irish seaboard, where the cliff itself serves as a natural defensive boundary, with an earthwork or stone rampart completing the enclosure on the landward side. Westropp was a prolific documenter of such sites across Munster and his observations, even when sceptical, carry weight. His doubt about whether the opening truly qualified as a souterrain entrance has not been resolved in the century since he noted it down, and no subsequent investigation appears to have clarified matters.