It measures roughly ten metres long, two and a half metres wide, and less than a metre deep, and it may be all that is visible of a souterrain, an underground stone-lined passage or chamber typically built during the early medieval period in Ireland, used variously for storage, refuge, or ventilation.

A cashel is a dry-stone ringfort, a roughly circular enclosure defined by thick stone walls, and they are among the most common early medieval settlement types in the Irish landscape. The depression at Carrowclogh sits within one such enclosure and has been tentatively identified as a souterrain on the basis of its form, though no excavation appears to have confirmed its nature. Souterrains, when intact, are often found within ringforts and cashels precisely because they served the domestic life of those enclosures, offering cool, dark storage for foodstuffs or a place of concealment during raids. What survives at Carrowclogh is a collapse feature, the kind of linear hollow that forms when an underground structure falls in on itself over centuries, leaving the ground above it sunken and irregular.