Lough Erne or Loch Erne (pronounced , ) is the name of two connected lakes in County Fermanagh, Northern Ireland. It is the second-biggest lake system in Northern Ireland and Ulster, and the fourth biggest in Ireland. The lakes are widened sections of the River Erne, which flows north and then curves west into the Atlantic. The smaller southern lake is called the Upper Lough (as it is further up the river) or South Lough. The bigger northern lake is called the Lower Lough or North Lough. The town of Enniskillen lies on the short stretch of river between the lakes. The lake has 154 islands along with many coves and inlets. When windy, navigation on Lower Lough Erne, running for 26 miles almost to the Atlantic, can be something of a challenge with waves of open-sea dimensions. Shallow Upper Lough Erne, spreading southeast of Enniskillen for about 12 miles, is a maze of islands. The River Erne is 80ml (129 km) long and drains an area of about 4,350 km².