This underground passage stretches just over 8 metres in length, running from south-southwest to north-northeast, and demonstrates the resourcefulness of Ireland's ancient inhabitants who transformed geological features into functional structures. The passage gradually widens as it extends northward, starting at 73cm at its southern entrance and expanding to 84cm at the northern end.

The souterrain's construction reveals careful planning despite its modest dimensions. The ceiling height varies considerably throughout; at the northern end it measures 1.35 metres, rises to 1.8 metres near the centre, then slopes down to just one metre at the southern entrance, creating an undulating roofline that follows the natural contours of the rock. Whilst approximately 5 metres of the passage remains open to the sky, the rest maintains its original flagstone roof, with packing stones still visible at the northern end where they help support the ceiling slabs.

Near the northern terminus of this subterranean chamber, ancient builders carved out a single niche in the floor, measuring 80cm wide, 75cm high and extending a metre deep into the rock. This alcove likely served as storage space for provisions or valuables, though its exact purpose remains a matter of speculation. The souterrain sits amongst rocky outcrops surrounded by pastoral fields, a setting that has probably changed little since it was first hewn from the stone centuries ago, offering visitors a tangible connection to Donegal's mysterious past.