A souterrain, discovered in the early part of the twentieth century, once ran east to west through the earth here, stone-built, roughly 1.75 metres high, and described at the time as extensive. No visible trace survives today.

Souterrains are underground stone-lined tunnels or chambers, typically associated with early medieval settlement in Ireland, and thought to have served variously as places of refuge, storage, or concealment. The one at Na Cluainte was found approximately 275 metres north-north-east of a recorded archaeological site nearby, suggesting it may have formed part of a wider complex of early activity in the area. The detail we have comes from J. Cuppage's 1986 archaeological survey of the Corca Dhuibhne region, a thorough and still-valued catalogue of the Dingle Peninsula's ancient remains. That the passage was tall enough for a person to stand in, and aligned carefully along an east-west axis, points to something more than a rough pit; this was a deliberate and considered piece of construction, even if its builders and their reasons are now beyond recovery.

What makes the site quietly interesting is precisely its absence. The souterrain has left nothing on the surface, no depression, no scatter of stone, no crop mark visible to a passing walker. It exists now only in the written record of its discovery, a gap in the ground that briefly came to light and then effectively vanished again.