That label is almost certainly a misidentification, or at least an imprecise one. What they were almost certainly recording was a souterrain, an artificially constructed underground chamber or tunnel built during the early medieval period, typically associated with nearby settlement and used for storage, shelter, or refuge. The fact that it sits within the interior of a ringfort, a circular enclosure of roughly the same era, makes the identification all the more plausible. Souterrains and ringforts frequently occur together across Ireland, the underground space serving the community living within or beside the enclosure above ground.

The 1842 Ordnance Survey map is one of the most detailed records of the Irish landscape ever produced, and its notation of this feature, however loosely labelled, preserves something that was apparently still visible or known to local informants at the time. By the revised edition of 1916, the feature had disappeared from the map entirely, suggesting it may have become overgrown, collapsed, or simply less legible in the intervening decades. The ringfort with which it is associated is recorded separately. The souterrain itself is documented in C. Toal's "North Kerry Archaeological Survey", published in 1995, which drew together field evidence and earlier cartographic sources for the region.