The River Shannon, which divides Ireland into east (Leinster) and west (Connaught), has been an important waterway since antiquity. First mapped by Ptolemy, the 200 mile long river empties into the Atlantic Ocean in a western direction at Limerick, turning north in the city.
It is the longest river in the British Isles.
Lakes on the Shannon include Lough Allen, Lough Ree and Lough Derg. Tributaries include the River Suck and the River Brosna. There is a hydroelectric generation plant at Ardnacrusha belonging to the ESB.
Oliver Cromwell once said the Irish would go to "Hell or Connaught" when he spoke of the river.