That detail, passed down through local memory rather than excavation report, is almost all that survives of a souterrain that was, by any measure, unusually substantial.

Souterrains are underground stone-lined passages or chambers, typically associated with early medieval ringforts, the circular enclosed farmsteads that once dotted the Irish countryside in their thousands. They were used for storage, refuge, or both, and most are cramped, low affairs that demand hands and knees rather than upright movement. The one at Ballyshoneen sits within what appears to be a ringfort, though the enclosure itself has not been definitively confirmed. What local tradition has preserved is the striking claim that this particular souterrain was spacious enough to enter standing, which would put it well outside the ordinary run of such features. At some point, rather than being recorded in any systematic way, it was simply sealed. A concrete cap now sits over it, and whatever the passage contains remains unexamined below ground.