The depressions run for roughly eleven metres on a roughly east-northeast to west-southwest axis, and where the ground has given way slightly, the edges of large stone slabs are visible; almost certainly the roof lintels of a souterrain, an underground passage or chamber constructed from dry-laid stone, typically associated with early medieval settlement in Ireland and used variously for storage, refuge, or concealment.

In the 1930s, a Captain D. B. O'Connell recorded his way into the structure through an entrance just over two and a half feet square, flanked by upright stones, which opened into a chamber roughly fourteen feet long, four feet wide, and three and a half feet high. Those are tight proportions: a person could move through such a space only by crawling or crouching. A further depression lying about four metres to the south-southwest, with its own opening at the base, suggests the souterrain does not end where O'Connell's account does, and that additional passages or chambers may extend in that direction. Some of the roof slabs have shifted from their original positions, which accounts for the surface dips that make the site legible from above at all. The site is also noted in Waddell's 1970 survey of Kerry antiquities.