A roughly circular hole in the earth, measuring about two metres east to west and just under two metres north to south, opens down into a chamber that drops more than a metre before extending further in both directions. This is a souterrain, an artificially constructed underground passage or chamber built into the earth, most commonly associated with early medieval settlement in Ireland, where they served as places of refuge, storage, or concealment. The collapse that made this one visible was accidental; the structure itself was designed to stay hidden.

The hillock is densely overgrown with gorse, and the chamber below the opening is now inaccessible. What can be seen through the hole suggests the underground space continues to the north and to the south, though how far is not recorded. The situation is not entirely isolated: a second souterrain lies roughly 110 metres to the south-south-west, which raises the possibility that this hilltop was once a more substantial site of activity, with underground features serving a settlement or enclosure that has since vanished from the surface entirely. The views southward over Glengarriff Harbour would have made the position a useful one, whatever its original purpose.