A shallow depression sitting just east of the enclosure's centre is all that visibly hints at a souterrain below, one of those dry-stone underground passages or chambers that early medieval Irish communities built beneath their farmsteads, most likely for food storage or refuge.

The rath in question is the northernmost of the four grouped enclosures, lying on a south-east facing slope roughly 75 metres north of its nearest neighbour. The tradition of a souterrain on the site was recorded by J. Cuppage in the 1986 Dingle Peninsula Archaeological Survey, a substantial inventory of the Corca Dhuibhne region that documented the remarkable concentration of prehistoric and early medieval remains across that part of Kerry. The four raths on Corrin Hill are part of that broader pattern, a landscape that saw sustained settlement and land organisation over many centuries. Whether the depression east of centre genuinely marks the collapsed roof or entrance of a souterrain, or is the result of some other disturbance, has not been definitively established, and the feature remains a tradition rather than a confirmed structure.