This was formed due to the roof cave collapsing, with some parts collapsing around 1959. If you follow it around to the left, you come to the Aille cliffs and caves. During periods of rain the water rises, making entrance to the cave dangerous.
According to the annals of Loch Ce, in 1063 A.D., 160 people were hiding in the caves for safety and were suffocated – reportedly with the jewels of Connacht.
Before and during penal times mass was held here in secret, to be caught was to risk the death penalty. Watchmen were placed on the cliffs to spot the authorities.