A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlement in Ireland, and thought to have served as a place of refuge, storage, or both. This one sits within the north-western quadrant of a nearby ringfort, a circular enclosed farmstead of the early medieval period, and there is now no visible trace of it whatsoever from ground level.

The site was observed by Hartnett in 1939, who recorded that two openings to the souterrain were discernible at the time, one to the north-west and one to the south-east, both lying inside the rampart of the associated ringfort. That detail, the two openings positioned within the enclosure rather than breaking through it, suggests the souterrain was an integral part of the settlement rather than a later addition. Since Hartnett's observation, however, whatever openings once gave access to the underground structure have closed over entirely, leaving nothing for the eye to catch.