County Down includes the easternmost point of Ireland and is part of Ulster Province. It is a maritime county, bounded on the north by Belfast Lough and County Antrim, on the east by the Irish Sea, southeast by Dundrum Bay, and on the west by Newry Canal, Carlingford Lough, and Armagh. The area covered is 957 square miles.
The Mourne Mountains are in the southwest, culminating in Slieve Donard at 2786 feet. St Patrick is buried at Downpatrick, the county seat. Bangor is the largest city and chief port.