Strangford Lough is a large sea lough or inlet in County Down, in the east of Northern Ireland. It is the largest inlet in Ireland and the wider British Isles, covering 150 km2 (58 sq mi). The lough is almost fully enclosed by the Ards Peninsula and is linked to the Irish Sea by a long narrow channel at its southeastern edge. The main body of the lough has at least seventy islands along with many islets (pladdies), bays, coves, headlands and mudflats. It is part of the Strangford and Lecale Area of Outstanding Natural Beauty. Strangford Lough was designated as Northern Ireland's first Marine Conservation Zone in 2013, and has been designated a Special Area of Conservation for its important wildlife.
Strangford Lough is a popular tourist destination noted for its fishing and scenery. Towns and villages around the lough include Killyleagh, Comber, Newtownards, Portaferry and Strangford. The latter two straddle either shore of the narrow Strangford channel, and are connected by a car ferry.