A half-metre square opening in the crest of the bank offers a restricted glimpse into what appears to be an L-shaped souterrain, the term for a drystone-built underground passage or chamber typically associated with Irish ringforts, most likely used for storage, refuge, or both. The opening sits directly above the junction where two short sections of passage meet, one aligned roughly northeast to southwest, the other southeast to northwest. Each section runs for only a metre before hitting a blockage, and the walls, standing about half a metre high, are capped by at least two stone slabs.

The ringfort itself, known as Cahernagat or Cathair na gCat, is a roughly circular univallate structure, meaning it is enclosed by a single bank or wall rather than the multiple concentric earthworks found at higher-status sites. What makes its location genuinely arresting is the company it keeps. Gallarus Oratory, one of the best-preserved early Christian dry-stone oratories in Ireland, sits only about fifty metres to the west. The Saint's Road, an ancient pilgrimage route across the peninsula towards Mount Brandon, passes less than a hundred metres to the east. The souterrain and its ringfort sit, in other words, at a quiet convergence of early medieval sacred and domestic life. The site was surveyed and described by J. Cuppage as part of the Corca Dhuibhne archaeological survey published in 1986, which documented the extraordinary density of early historic and prehistoric remains across the Dingle Peninsula.