This souterrain, a type of underground passage typical of early medieval Ireland, consists of a series of rock-cut chambers connected by narrow manholes. The entrance itself is barely large enough for a child to squeeze through; a small, irregular opening measuring just 45 centimetres at its widest point leads into what appears to be a westward-extending passage carved directly from the bedrock.

First documented in detail by local schoolchildren in 1938, the souterrain originally contained five chambers, four of which remain accessible today. The dimensions recorded by those early explorers paint a picture of cramped, purposeful spaces: the first chamber measures 11 feet long, 3 feet broad and 3 feet high, whilst the second extends to 16 feet in length, with slightly more generous proportions of 4 feet 2 inches wide and 4 feet 6 inches high. The third chamber falls somewhere between the two at 15 feet long, 5 feet broad and 4 feet high. Moving between these spaces requires crawling through connecting manholes, with one passage so narrow that visitors must proceed on hands and knees.

Despite their age and underground location, the chambers maintain surprisingly good air quality, suggesting some form of natural ventilation system within the rock. In wet weather, a small amount of water collects in the first chamber but quickly drains away, whilst during dry spells the entire complex remains bone dry. Stone slabs that once concealed the entrance now rest against a nearby field boundary, and fallen stones from the ceiling litter the floors; testament to centuries of weathering. Local boys who've recently explored the site report that the passages have 'thin walls' and lack artificially constructed roofs, indicating that whoever created this mysterious complex worked entirely with the natural rock formation.