The operative phrase is "may or may not": the cavity said to mark the entrance has long since disappeared into the vegetation, leaving behind little more than a persistent local tradition and a ninety-year-old academic footnote.

A souterrain is a man-made underground passage or chamber, typically associated with early medieval ringforts, a ringfort being a roughly circular enclosure defined by earthen banks and ditches that served as a farmstead during the early Christian period in Ireland. They were common across the country, and many contained souterrains used for storage, refuge, or both. At Coolanagh, the archaeologist Seán P. Ó Ríordáin noted in 1933 that a cavity at the centre of the ringfort was pointed out by locals as the entrance to underground chambers. Whether those chambers genuinely exist, and in what condition, remains unconfirmed. By the time the site came to be more formally documented, no visible trace of the cavity could be found in the now heavily overgrown interior.

What remains, then, is the oral tradition itself, the fact that someone in the early twentieth century knew to point a visiting scholar toward a particular spot in the ground and say: there, that is where you go down. That kind of local memory, persisting long after physical evidence has been swallowed by undergrowth, is not unusual in the Irish landscape, where the human past has a tendency to survive as story when it can no longer survive as structure.