Lough Nanoge
| River Shannon (Abhainn na Sionainne) | |
| River | |
 River Shannon from Drumsna bridge, County Leitrim
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| Country | Ireland |
|---|---|
| Counties | Cavan, Leitrim, Roscommon, Longford, Offaly, Westmeath, Galway, Clare, Tipperary, Limerick, Kerry |
| Source | Shannon Pot |
| - location | Dowra, Cuilcagh Mountain, County Cavan |
| - elevation | 100 m (328 ft) |
| - coordinates | 54°14′06″N 7°55′12″W / 54.235°N 7.92°W |
| Mouth | Shannon Estuary |
| - location | Limerick |
| - coordinates | 52°39′25″N 8°39′36″W / 52.657°N 8.66°WCoordinates: 52°39′25″N 8°39′36″W / 52.657°N 8.66°W |
| Length | 360.5 km (224 mi) |
| Basin | 6,060 sq mi (15,695 km2) |
| Discharge | |
| - average | 208.1 m3/s (7,349 cu ft/s) |
The River Shannon (Irish: Abha na Sionainne, an tSionainn, an tSionna) is the longest river in Ireland at 360.5 km (224 miles). It drains the Shannon River Basin which has an area of 16,865 km2 (6,512 sq mi), one fifth of the area of Ireland.
The Shannon divides the west of Ireland (principally the province of Connacht) from the east and south (Leinster and most of Munster). County Clare, being west of the Shannon but part of the province of Munster, is the major exception. The river represents a major physical barrier between east and west, with fewer than thirty crossing-points between Limerick city in the south and the village of Dowra in the north.
The river is named after Sionna, a Celtic goddess.
The Shannon has been an important waterway since antiquity, having first been mapped by the Graeco-Egyptian geographer Ptolemy. The river flows generally southwards from the Shannon Pot in County Cavan before turning west and emptying into the Atlantic Ocean through the 102.1 km (63.4 mi) long Shannon Estuary. Limerick city stands at the point where the river water meets the sea water of the estuary. The Shannon is tidal east of Limerick as far as the base of the Ardnacrusha dam.
By tradition the Shannon is said to rise in the Shannon Pot, a small pool on the slopes of Cuilcagh Mountain in County Cavan, from where the young river appears as a small trout stream. Surveys have defined a 12.8 km2 (4.9 sq mi) immediate pot catchment area covering the slopes of Cuilcagh. This area includes Garvah Lough, Cavan, 2.2 km (1.4 mi) to the northeast, drained by Pollnaowen. Further sinks that source the pot include Pollboy and, through Shannon Cave, Pollahune in Cavan and Polltullyard and Tullynakeeragh in County Fermanagh, Northern Ireland. The highest point in the catchment is a spring at Tiltinbane on the western end of the Cuilcagh mountain ridge.
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Wikipedia