Lough Erne, a lake of Ireland, county Fermanagh, consisting of two sheets of water, called the upper and lower lakes, connected by a narrow winding channel. It is fed by the river Erne, which, rising in Lough Gowna, flows N. through county Cavan, and expands near Crum into the upper lake. This is about 12 m. long, from 2 to 2 1/2 m. wide in its broadest part, and has a general depth of 20 ft., although in some places it is 75 ft. deep. There are 90 small islands in it, and the shores are generally low and marshy. The lower or northern northerly lake is 20 m. long, from 2 m. to 5 m. wide, and has a depth in some places of 225 ft. It contains 28,000 acres, and has 109 islets; Boa island, the largest, near the N. end, contains 1,300 acres. Both lakes abound with fish. The town of Enniskillen is partly situated on an island in the connecting channel, and there are a number of handsome residences and some well preserved ruins along its banks. The river leaves the 1ST. end of the lower lake, and after a course of 8 m. empties into Donegal bay.