East of the stone fortress of Dún Aonghasa on Inis Mor is a prime example of what is slowly eating the Aran Islands. The limestone cliffs are constantly pounded by the Atlantic waves. Eventually, the waves carve small, and then, larger, caves under the cliffs before eventually demolishing them. In this case, near Poll na bPéist, the waves drive compressed air into a cave which expolodes out, like a demon. If you look at the ledge to the left of the spray, you’ll see a man in a blue teeshirt which will give you an idea of the size of the plume.
On the top of the cliff is a pile of rough-hewn boulders – a line of debris caused by the waves chipping away at the cliff, and an indication of how ferocious the sea can be.