Poll na bPéist or the Worm Hole as it is otherwise known is a striking natural rectangular shaped pool at the bottom of the cliffs, south of Dún Aonghasa. It gets it name from ‘péist’ which is the reptilian sea monster from Gaelic folklore.
The unusual rock formation also has underground channels which link up to the sea. The water rushes into the Wormhole through an underground cave, or when the tide is high, spills over and fills it up from above.
Since 2012, the wormhole has been used as a venue for the popular Red Bull Cliff Diving World Series.