This subterranean complex consists of two stone passages arranged at right angles to each other, connected by a narrow crawl space known as a creep. The main passage stretches 15.5 metres in a north-northeast to south-southwest direction, whilst a secondary passage runs 8.67 metres from west-northwest to east-southeast. Both passages showcase the impressive drystone construction techniques of their builders, with walls that corbel inwards and massive stone slabs forming the roof.

The craftsmanship of this underground structure reveals careful planning and skilled execution. Passage I varies in width from 1.77 metres at its widest point to just over a metre at its northern end, with walls narrowing from 1.15 metres at the base to 0.67 metres at the top, reaching a maximum height of 1.54 metres. The connecting creep, positioned at the centre of the main passage's wall, requires visitors to squeeze through an opening that's barely half a metre wide and less than 0.7 metres high. Passage II maintains similar construction methods but includes intriguing features such as two recesses carved into its walls; one partially cut into bedrock and another with a clay backing, alongside a small drainage channel at its base.

Time has taken its toll on this ancient structure, with silt gradually filling portions of both passages and a breach in the roof now serving as the modern entrance rather than whatever original entry point once existed. A low sillstone crosses the width of Passage II, possibly serving as a threshold or division marker within the space. Located in the drumlin landscape characteristic of County Donegal, this souterrain represents one of many such structures found across Ireland, likely built as places of refuge, storage, or both during troubled times in the medieval period.