It is partially overgrown, filled with stone, and measures roughly 6.8 metres north to south and 3.6 metres east to west. What it marks, however, is the collapsed remains of a souterrain, an underground stone-built passage or chamber constructed during the early medieval period, typically used for cold storage, refuge, or both. The site sits close to the northwest stone bank of the enclosing cashel, a cashel being a circular stone-walled enclosure of the kind built by farming communities and minor lords across early medieval Ireland.

The association between souterrains and cashels is well established in the Irish archaeological record. Souterrains were usually built in conjunction with the settlement above them, their entrances carefully concealed and their chambers corbelled or lintel-roofed with local stone. Over centuries, as the timbers or capstones gave way, the roof would collapse inward and the cavity fill with rubble, leaving precisely the kind of stone-choked hollow visible here at Liscarroll. The proximity to the northwest bank suggests the souterrain was positioned to make use of the cashel wall as part of its structural context, a common enough arrangement where the enclosure itself offered additional cover and concealment.