A souterrain is an underground stone-lined passage or chamber, typically associated with early medieval settlements in Ireland, often used for storage or refuge. The difficulty here is that nobody has been able to confirm this one exists at all, which makes it a quietly peculiar entry in the archaeological record: a structure defined almost entirely by a single act of recording, and by the absence of anything to show for it.

In the 1930s, a Captain D. B. O'Connell noted the presence of a souterrain at this location. That observation was logged, and there the trail essentially ends. No excavation appears to have followed, no surface features survive, and no visible remains have since been identified. The site sits with views to the south-east towards The Paps of Dana, the twin rounded hills long associated in Irish mythology with the goddess Anu, which lend the landscape a particular quality of oldness. Whether O'Connell encountered a collapsed entrance, local knowledge, or a feature that has since been obscured by time and grazing land is unknown. The qualifier "possible" attached to the souterrain in the archaeological record says everything about how much remains uncertain.