That is, more or less, the situation at Lounaghan in County Kerry, where a hollow opened up along a cattle path beside a ringfort, and the question of what exactly lies beneath has not been straightforwardly answered since.

Souterrains are stone-lined underground passages or chambers, built during the early medieval period and typically associated with ringforts, the circular enclosed settlements that dot the Irish countryside in their thousands. They were used variously for storage, refuge, or both. The cavity at Lounaghan sits roughly 70 centimetres from the outer base of the ringfort's bank, along a path that appears to have been roughly paved with flags and small boulders at some point. The hole itself is modest: 49 centimetres deep, 30 centimetres north to south, 40 centimetres east to west, with a large limestone boulder about 70 centimetres long immediately to its east. There were no further openings inside suggesting chambers or creepways, which would ordinarily be the defining features of a true souterrain. The alternative explanation is mundane: an animal burrow, collapsed under the regular pressure of hooves. The landowner had the impression that the ringfort bank to the north had subsided over the years, but there is a more prosaic explanation for that too, since cattle have been accessing the interior of the ringfort at this point and the apparent sinking of the bank may simply be erosion caused by the animals themselves.