The river Shannon drains one fifth of the land area of Ireland, its length of 370 kilometers (230 Miles) makes it the longest river in Ireland and also the British Isles, if you add in the tributaries its length is 1,818 kilometers (1,130 Miles) It rises out of a hole in the limestone bedrock of County Cavan, 'The Shannon Pot' in the Cuilcagh Mountains 667 Meters(2,188 feet) on its way to the Atlantic if flows to the Southwest through three major lakes Allen, Ree and Derg and ten of Ireland's thirty-two counties. At the city of Limerick which is about 100 kilometers (62 Miles) from the mouth of the Shannon the river becomes tidal, there are ports at Limerick and Foynes.

It gets its name from Sionna, the grand daughter of the Celtic sea god Lir. The the river is a very popular pleasure cruising area. There is a hydroelectric generation plant at Ardnacrusha belonging to the ESB.

It was in the last ice age the river was born. Vikings settled in the area in 10th century and used the river to raid the rich monasteries deep inland. In 937 the Limerick Vikings defeated those of Dublin on Lough Ree. The term 'Hell or Connaught' comes from a statement Oliver Cromwell once made when expelling Irish clans from the eastern counties to west of the Shannon.

It is possible to travel by cruiser from the Shannon to Dublin via the Grand and Royal canals which were built in the late 1700's and early 1800's. The Shannon Erne waterway which was reopened in 1994 gives access to Lough Erne, the river is navigable up to quite near its source.

Major tributaries of the Shannon: Deel, Brosna, Inny, Suck and the Maigue.

together with the Carnadoe and Boyle Waters with seven locks. A further 70 miles (113 km) from Killaloe to the sea at Loop Head through Limerick with one double lock at Ardnacrusha Power Station. Navigation administration by Waterways Ireland, 17 / 19 Lower Hatch Street, Dublin 2 Tel. 01-647 2535 and boats are required to be registered ( no charge) with engines of over 10bhp.

Boat dimensions: Killaloe to Lough Key 102 ft (31m) x 30 ft (9m) x 5 ft (1.5m), River Camlin and Lough Allen Canal 64 ft (19.5m) x 13 ft (4m) x 4 ft (1.2m), Killaloe to Limerick 100 ft (30m) x 18 ft (5.5m) x 5 ft (1.5m).

Headroom: Minimum clearance at fixed bridges at normal summer levels Killaloe to Lough Key 13 ft (4m), River Camlin 12 ft (3.7m), Killaloe to Limerick 11 ft (3.4m). Swing or lifting bridges at Portumna 4 ft (1.2m), Tarmonbarry 9 ft (2.7m), Roosky 11 ft (3.3m), in closed positions.

Slipways: Facilities for larger craft at Killaloe, Portumna, Banagher, Athlone, Inner Lakes (Lough Ree), Carrick-on -Shannon. For smaller craft at Garrykennedy, Dromineer, Mountshannon, Terryglass, Rossmore, Portumna Castle, Hodson Bay, Barley Harbour, Roosky, Dromod Harbour, Jamestown. For rowing boats at Kilgarvan, Athlone, Portrunny, Lanesbrough, Kilglass, Acres Lake, Cootehall, Rockingham.

Dry docks: Killaloe, Clondara and Roosky.

Charges: €1.50 per lock or opening bridge paid to the keeper.