The depression stretches more than 23.5 metres in total, and while the structure has long since collapsed, two possible roof lintels still lie in situ among the fallen stone, hinting at how the passage once held itself together. A souterrain is a stone-lined underground tunnel or chamber, typically built during the early medieval period as a place of refuge, storage, or concealment, and this one is an unusually substantial example of the type.

The souterrain sits within the WNW sector of a rath, the earthen ringfort with which it was originally associated. Raths were enclosed farmsteads of the early medieval period, and souterrains were commonly built inside or beneath them, accessible from within the enclosure. This particular passage follows an L-shaped plan: the longer arm runs roughly northeast to southwest, measuring 13 metres in length and 1.8 metres in width, while a shorter arm of 10.5 metres, slightly wider at 2.4 metres, branches off from the southeast end and runs northwest to southeast. The geometry suggests a deliberately planned structure rather than a simple trench, with the angled layout possibly designed to disorient intruders or to regulate temperature and airflow for storage purposes.