A souterrain is an underground passage or chamber, typically built from stone, associated with early medieval Irish settlements and used variously for storage, refuge, or ventilation. The one recorded here is notable precisely for its absence: when inspectors visited the cashel in October 1998, they found no visible surface trace of it whatsoever.

The site sits within, or immediately associated with, a cashel, which is a stone-walled ringfort of the kind common across early medieval Ireland. The souterrain was noted on an annotated map in 1992 and formally listed in the Record of Monuments and Places in 1996, yet when the ground was examined in person two years later, whatever entrance, depression, or lintel might once have betrayed its presence had either collapsed, been buried, or was simply undetectable. This leaves the feature in an awkward archival limbo: recorded as existing, yet physically unverifiable. It is not unusual for souterrains to become invisible over centuries, as roof slabs settle and soil accumulates, but that process makes the record simultaneously more interesting and more frustrating.