The one at Dunisky in County Cork is different. Carved directly into a natural outcrop of old red sandstone, its seven chambers were not built so much as hewn, their barrel-vaulted roofs cut from the living rock. The whole complex sits immediately south of the site of Dunisky church and graveyard, a proximity that turns out to be significant.

The souterrain was discovered in 1927, though it took until 1930 for anyone to get inside it properly. Access was eventually gained with the help of explosives, after which L. S. Gogan of the National Museum of Ireland carried out an investigation. A more detailed account followed in 1977, when J. P. McCarthy published a chamber-by-chamber description of the interior. What he found was a warren of interconnected spaces linked by creepways, the low, narrow connecting passages that required anyone moving between chambers to crouch or crawl. The layout is complex: chamber three, for instance, opens onto both chamber four and chamber five through creepholes set opposite each other in its north and south walls, effectively making it a junction. Several chambers retain rock-cut ledges and benches along their walls, and chamber six, oval in plan with a sloping floor, has a square hole in its floor at the south-east corner, silted up, and possibly once a well. The finds were sparse but suggestive: a mallet head recorded by Gogan, and two portions of a furnace bottom found by McCarthy. McCarthy considered the souterrain atypical of the form and proposed a twelfth-century date, reading its unusual character and its closeness to the church as evidence of an ecclesiastical rather than a purely domestic origin.