Belfast Lower is a barony in County Antrim, Northern Ireland. To its east lies the east-Antrim coast and Belfast Lough, and it is bordered by four other baronies: Belfast Upper to the south; Carrickfergus to the east; Antrim Upper to the west; Glenarm Upper to the north. The Forth and Milewater rivers both flow through Belfast Lower, with Larne harbour also situated in the barony.