8Barry, T.B., S. Diarmond, T.D. Shanley, Maura Scannell, and Edelgard Soergel-Harbison. "Arch├Žological Excavations at Dunbeg Promontory Fort, County Kerry, 1977." Proceedings of the Royal Irish Academy. Section C: Archaeology, Celtic Studies, History, Linguistics, Literature 81C (1981): 309-11.
The authors write, "The northern end of the souterrain is marked by a semi-circular wall with a possible small ventilation shaft at roof level...On the balance of probability the souterrain, which lacks any chambers or abrupt changes in floor level, would probably have been a place of refuge for the defenders of the fort. It would have been quite a simple matter to seal off its southernmost entrance inside the rampart with one of the smaller floor slabs of the entrance-way. The last defender into the souterrain would have had to fit this capstone in very tightly between its neighbours so that the souterrain underneath would remain undetected even after the fort had been captured."