Lough Eske or Lough Eask (from Irish Loch Iascaigh or Loch Iasc, meaning "Lake of the Fish") is a small lake in County Donegal in the west of Ulster in Ireland. The lake lies to the northeast of Donegal Town, to which it is connected by the River Eske. The lake is about 900 acres (3.6 km2) in size and is surrounded to the north, east and west by the Bluestack Mountains, which occupy much of southern County Donegal.