Achill Island is an island off the west coast of Ireland in the historical barony of Burrishoole, County Mayo. It is the largest of the Irish isles and has an area of approximately 148 km2. Achill had a population of 2,345 in the 2022 census. The island, which has been connected to the mainland by a bridge since 1887, is served by Michael Davitt Bridge, between the villages of Achill Sound and Polranny.