In the 1940s, a local account described a flagged underground passage stretching for approximately a quarter of a mile, with rooms branching off along its length and two separate entrances opening up from the surrounding earthwork. That would make it a remarkable structure by any measure, far exceeding the typical dimensions of an Irish souterrain. The problem is that nothing of it can be seen today.

Souterrains are dry-stone or rock-cut underground passages, sometimes with chambers, built during the early medieval period and most often associated with ringforts, the circular enclosed farmsteads that dot the Irish countryside. The earthwork here at Toormore, known as a rath, is precisely that kind of settlement, and souterrains built within raths are well attested across Ireland. They were used variously for storage, refuge, or both. What was recorded in the 1940s, apparently from local knowledge, was a passage of unusual scale: flagged underfoot, branching into rooms, and entered from two points within the rath enclosure. The account comes from the Schools Manuscript collection, a nationwide folklore-gathering project of that era in which schoolchildren recorded local knowledge from older community members. Such sources are invaluable precisely because they preserve details that survive nowhere else, though they can also conflate memories or describe structures that were already in poor condition.

Whether the full quarter-mile passage ever existed as described, or whether the account gathered several features, embellished a smaller structure, or accurately captured something now entirely collapsed and buried, is impossible to say from the surface. No visible remains survive at the site today.