The structure was discovered in 1958, but it was closed before anyone could carry out a formal inspection. What survives in the record is secondhand: a passage leading to what appears to have been a beehive-shaped chamber, its walls lined with stone, its interior unexamined and unrecorded. There is no visible trace of it on the surface today. The ground above gives nothing away.

The structure belongs to a category of underground monument known as a souterrain, a type found widely across early medieval Ireland and typically associated with nearby settlement. Souterrains were built, usually between roughly the seventh and twelfth centuries, as stone- or timber-lined underground passages and chambers, most likely used for storage, refuge, or both. The beehive-shaped chamber described at Ballyvoskillakeen, if that description is accurate, points to a corbelled construction technique, in which courses of flat stone are laid in progressively narrowing rings to form a domed roof without mortar. That detail comes not from direct observation but apparently from the account of whoever encountered the structure in 1958 before it was sealed. The reference in McCarthy's 1977 survey, citing the University College Cork record, is the closest thing to a primary source that exists for this site.