This one is notable almost entirely for what does not. At Coolroe in County Kerry, a souterrain, which is an underground passage or chamber typically built during the early medieval period for storage or refuge, once lay visible at the centre of a rath. A rath is a circular earthen enclosure, usually surrounding a farmstead, and was one of the most common settlement types in early medieval Ireland. Both the rath and the souterrain within it have since been levelled, leaving no surface trace of either structure.

What is known comes largely from local memory rather than any formal investigation. Before the rath was destroyed, the souterrain opening was reportedly visible in the interior of the enclosure. The site is recorded as a possible souterrain rather than a confirmed one, which reflects the difficulty of classifying something that cannot now be examined directly. The rath itself is catalogued separately, suggesting the two features were once understood as parts of the same farmstead complex, the underground chamber serving the household that lived within the enclosure above.