Aasleagh Falls is a small but satisfying stop a few minutes north of Leenane, where the Erriff River drops over a low ledge before entering Killary Harbour. It is not a huge waterfall, but the setting makes it work: open valley, mountain backdrop, and dark peaty water after rain.
The visit is quick unless you linger for photographs or continue walking along the river. It pairs naturally with a drive into the Delphi Valley.