CAUTION: The entrance to Poll na Gollum is a hole a hundred feet deep and close to the cache. Take extreme care at the entrance and do not leave children or dogs unattended. You might find a climbing rope attached to a rock close to the entrance - do not take the rope, it indicates that a group is currently exploring the cave. If you are planing to explore the cave make sure you bring the right equipment, do not approach the cave on your own and inform someone.
The Burren is home to the largest cave system in Ireland, the entrance of which lies about four miles from Gregan's Castle. It comprises of 15 miles of underground passages. This entrance is called Poll na Gollum (translated from the Irish as the Hole of Gollum).
It is said that one of J. R. R. Tolkien's best known characters in his masterwork 'The Lord Of The Rings', Gollum, is named after Poll na Gollum in the Burren. 'Gollum' in Irish means 'rock dove', and the favourite habitat for these birds is cliff edges - the other coincidence is that rock doves make a guttural sound, same as Gollum in the book.
Enjoy the spirit of this special place and don't forget to bring your camera ;-)