What lies beneath is a souterrain, an underground passage or chamber typically constructed during the early medieval period in Ireland, used for storage, refuge, or both. What makes this one quietly arresting is the way it revealed itself not through deliberate excavation but through the accidental exposure of a newly made cutting, which sliced through the structure and left three raw openings blinking in the Kerry light.

The largest of the three openings, around two metres wide, gives access to a downsloping passage just over a metre high, its sides sloping inward and its roof curved, cut directly from the clay and gravel subsoil rather than lined with stone. This is a reasonably common construction method for souterrains in Munster, where the geology permitted digging rather than dry-stone building. The passage runs roughly seven metres westward before it is partially blocked by a loose pile of stones, some of them water-rolled, suggesting they may have been gathered from a nearby stream. At that point, a small aperture in the roof allows a narrow column of light into the interior. Beyond the blockage, the passage curves southward and loops back to the south-westernmost opening, forming something close to a circuit. A second, smaller passage branches northward from the middle opening, crosses the main tunnel, and continues for about one and a half metres before turning west, though this branch is inaccessible. The result is a modest but genuinely complex underground network, branching and curving beneath an otherwise unremarkable field.

The three openings visible on the scarp face vary considerably in size, from the large entrance down to a gap barely a tenth of a metre high, and at least one is partially obscured by a large stone. A visitor approaching across the pasture would see little to suggest what lies underfoot until standing almost directly on the exposed edge.