Just 85 centimetres wide and 55 centimetres high, the opening cuts under the inner face of the western wall and descends into the ground, heading northwest into darkness. It is, by any measure, a tight fit, and that was almost certainly the point. Souterrains are stone-lined underground passages or chambers built during the early medieval period in Ireland, most commonly associated with ringforts and settlement enclosures. Their exact function is debated, but storage, refuge, and concealment are the most plausible explanations, and an entrance that forces a grown adult to crawl offers an obvious defensive logic.

The hut site containing the souterrain sits within a rath, the Irish term for a ringfort, a type of enclosed farmstead typically dating from roughly the sixth to the twelfth century. These layered structures, a souterrain inside a dwelling inside a defended enclosure, suggest a settlement with some concern for security, and the underground passage would have added another layer of that. The opening is now blocked with stones, making the souterrain inaccessible, which is a reasonable precaution given that the interior has not been documented in any detail available here.