The Irish Sea (Irish: Muir Éireann) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man.
The Irish Sea is widest in its centre, stretching approximately 230 kilometres (143 mi) from Blackrock, Ireland to Morecambe, England on the eastern shoreline. It is narrowest in the north, approximately 20 kilometres (12 mi) separating Northern Ireland from Scotland.