That, in a way, is exactly the point. Somewhere beneath the grass and soil, local tradition holds that a network of underground chambers once ran through the headland, though the site is now fully filled in, with no surface trace remaining to betray its presence.

The structure in question is a souterrain, a type of man-made underground passage or chamber constructed during the early medieval period in Ireland, typically from dry-laid stone. Souterrains served various purposes, most likely for cool storage of foodstuffs and possibly as places of refuge. They were often associated with nearby settlements or ringforts, though no such companion features are mentioned here. What survives at Farranamanagh is not the archaeology itself but the memory of it, passed down through local oral tradition. The promontory setting, extending into the lough, would have made for a naturally defensible or secluded position, which fits the broader pattern of early medieval activity in such landscapes.