Carlingford Lough (Irish: Loch Cairlinn, Ulster Scots: Carlinford Loch) is a glacial fjord or sea inlet in northeastern Ireland, forming part of the border between Northern Ireland to the north and the Republic of Ireland to the south. On its northern shore is County Down, the Mourne Mountains, and the town of Warrenpoint; on its southern shore is County Louth, the Cooley Mountains and the village of Carlingford. The Newry River flows into the loch from the northwest.