A souterrain, to use the proper term, is an artificially constructed underground tunnel or chamber, typically associated with early medieval settlement in Ireland, and thought to have served as storage space, refuge, or both. What makes this particular example worth attention is its complexity: three passages, each separately oriented, joined by lintelled creepways so tight that a person would have to squeeze through flat, the smallest measuring just half a metre wide by thirty centimetres high.

The souterrain sits within the northwest quadrant of the caher, a type of stone-walled enclosure common across the Iveragh Peninsula. Entry to the system begins through an opening of 0.7 metres by 0.6 metres, leading into a north-south passage 3.3 metres long, its earthen sides roofed with stone slabs. A creepway at the southern end connects to a second passage, this one running NNE to SSW and slightly more generous in height at 1.3 metres, though barely half a metre wide. A further creepway leads to a third passage, aligned east-west and around three metres long, its walls built in coursed drystone masonry with intermittent upright slabs. This third section is now inaccessible. A researcher named O'Connell, working for the Office of Public Works in 1937, was able to enter the souterrain through an opening at the east end of this passage, a point then located in the south-east outer wall of the caher. That entrance has since been buried under field clearance material, the slow accumulation of stones shifted off surrounding land over the decades.