No hollow in the soil marks it, no lintel stone protrudes, no tradition of local use keeps it in public memory. It exists, officially, because someone noted it down on a single autumn day in 1977, and that record is very nearly all there is.

Souterrains are stone-lined underground chambers and tunnels, usually associated with early medieval settlement in Ireland, thought to have served as places of refuge, storage, or concealment. They turn up under raths, beside ringforts, and occasionally beneath later farmsteads built unknowingly on top of earlier occupation. The Ballyhass example was recorded in UCC topographical files on 30 September 1977, with no further detail attached, no dimensions, no description of construction, no note of how it was discovered or who first noticed it. It sits in a farmyard, meaning the land above it has continued to be used in the ordinary way, with no visible surface trace remaining to suggest anything lies below. Whether the souterrain is intact, partially collapsed, or long since disturbed is simply not known from what survives on record.