The Puffing Holes are one of the wilder little stops on Inis Mor, set on the island's exposed south coast where the Atlantic works its way through cracks in the limestone. In rough weather the sea booms below and throws spray up through the holes; in calmer conditions the drama is quieter, but the bare rock and ocean edge still feel very far from the ferry pier.
Treat this as a walk rather than a quick roadside sight. The ground is uneven, the edges are not fenced, and the reward depends heavily on tide and swell, so keep well back from openings in the rock. It pairs naturally with a cycling or walking circuit of the island's prehistoric forts and cliff scenery.