The entrance, by local tradition, once opened somewhere in or close to the inner face of the south-eastern bank of the enclosure, but that opening has long since disappeared from view, leaving the passage, if it survives at all, sealed off entirely.

A rath is a ringfort, typically an enclosed farmstead of the early medieval period, defined by one or more earthen banks and ditches. Souterrains, which are man-made underground passages or chambers usually constructed from stone, are found in association with raths across Ireland and are thought to have served as places of refuge or cool storage. The one at Quigabar is known only through local memory rather than any excavation or physical survey, and the tradition recorded simply notes that the access point lay along the inner bank face to the south-east. Whether the opening collapsed, was deliberately blocked, or was gradually obscured by centuries of vegetation and soil movement, is not recorded.