Achill_Island Achill Island (; ) in County Mayo is the largest island of Ireland, and is situated off the west coast. It has a population of 2,700. Its area is . Achill is attached to the mainland by Michael Davitt Bridge, between the villages of Gob an Choire (Achill Sound) and Poll Raithnà (Polranny), so it is possible to drive onto the island (as of August 2008, this bridge is undergoing renovation, and a temporary causeway is in place).