Lake, Fermanagh district, Northern Ireland .
An average of 5 mi (8 km) wide, the lake consists of the shallow Upper Lough Erne, 12 mi (19 km) long, and Lower Lough Erne, 18 mi (29 km) long, linked by a 10-mi (16-km) strait that is part of the River Erne. Numerous islands dot the lakes and provide recreation facilities. The River Erne, which flows north across the border of Northern Ireland and empties into Donegal Bay, is 72 mi (116 km) long.