River Shannon in the context of "Geography of Ireland"

Shown here are all the major rivers and tributaries of Ireland with their lengths (in kilometres and miles). Starting with the Northern Ireland rivers, and going in a clockwise direction, the rivers (and tributaries) are listed in regard to their entry into the different seas: the Irish Sea, the Celtic Sea and the Atlantic Ocean. Also shown are two tables. Table 1 shows the longest rivers in Ireland with their lengths (in kilometres and miles), the counties they flow through, and their catchment areas (in square kilometres). Table 2 shows the largest rivers in Ireland (by mean flow) in cubic metres per second.

The longest river in Ireland is the River Shannon, at 360.5 kilometres (224.0 mi). The river develops into three lakes along its course, Lough Allen, Lough Ree and Lough Derg. Of these, Lough Derg is the largest. The Shannon enters the Atlantic Ocean at the Shannon Estuary. Other major rivers include the River Liffey, River Lee, River Swilly, River Foyle, River Lagan, River Erne, River Blackwater, River Nore, River Suir, River Barrow (The Three Sisters), River Bann, River Slaney, River Boyne, River Moy and River Corrib.

The Royal Canal (Irish: An Chanáil Ríoga) is a canal originally built for freight and passenger transportation from Dublin to Longford in Ireland. It is one of two canals from Dublin to the River Shannon and was built in direct competition to the Grand Canal. The canal fell into disrepair in the late twentieth century, but much of it has since been restored for navigation. The length of the canal to the River Shannon was reopened on 1 October 2010, but a final spur branch, to Longford Town, remains closed.

Limerick (/ˈlɪmərɪk/ LIM-ər-ik; Irish: Luimneach [ˈl̪ˠɪmʲ(ə)nʲəx]) is a city in western Ireland, in County Limerick. It is in the province of Munster and is in the Mid-West which comprises part of the Southern Region. With a population of 102,287 at the 2022 census, Limerick is the third-most populous urban area in Ireland, and the fourth-most populous city on the island of Ireland. It was founded by Scandinavian settlers in 812, during the Viking Age.

The city straddles the River Shannon, with the historic core of the city located on King's Island, which is bounded by the Shannon and Abbey Rivers. Limerick is at the head of the Shannon Estuary, where the river widens before it flows into the Atlantic Ocean. Limerick City and County Council is the local authority for the city.

Lough Allen (Irish: Loch Aillionn) is a lake on the River Shannon in northeastern Connacht, Ireland. Most of the lake is in County Leitrim, with a smaller part in County Roscommon. The lake lies to the south of the River Shannon's source, near the Iron Mountains, and is the uppermost of the three main lakes on the river. The other two, Lough Ree and Lough Derg are much further to the south.

Lough Ree (Irish: Loch Rí), translated to English as King's Lake or King Lake, is a lake in the midlands of Ireland, the second of the three major lakes on the River Shannon. Lough Ree is the second largest lake on the Shannon after Lough Derg. The other two major lakes are Lough Allen to the north, and Lough Derg to the south. There are also several minor lakes along the length of the river. The lake serves as a border between the counties of Longford and Westmeath (both in the province of Leinster) on the eastern side and County Roscommon in the province of Connacht on the western side. The lake is popular for fishing and boating. The lake supports a small commercial eel fishery and is locally famous for its eels on wheels truck. The town of Athlone is situated at the southern end of the lake, and has a harbour for boats going out on the lake. The small town of Lanesboro is at the northern end of the lake.

The island of Inchcleraun (Inis Cloithreann) in the northern part of the lake is the site of a monastery founded in the early Christian era and contains the remains of several ancient churches. In Irish legends, it was on this island that Queen Maeve was killed. The Viking Turgesius controlled a ringfort on the shores until his death by drowning in Lough Owel.

Lough Derg, historically Lough Dergart (Irish: Loch Deirgeirt), is a freshwater lake in the Shannon River Basin, Ireland. It is the third-biggest on the island of Ireland (after Lough Neagh and Lough Corrib) and the second largest lake in the Republic of Ireland.

It is a long, narrow lake, with shores in counties Clare (south-west), Galway (north-west), and Tipperary (to the east). It is the southernmost of three large lakes on the River Shannon; the others being Lough Ree and Lough Allen. Towns and villages on Lough Derg include Portumna, Killaloe & Ballina, Dromineer, Terryglass, Mountshannon and Garrykennedy.

The Shannon Estuary in Ireland (Irish: Inbhear na Sionainne) is a large estuary where the River Shannon flows into the Atlantic Ocean. The estuary has Limerick City at its head and its seaward limits are marked by Loop Head to the north and Kerry Head to the south. The estuary defines the main boundary between County Kerry/County Limerick to the south and County Clare to the north.

The length of the Shannon Estuary is 102.1 km (63.4 mi). The Lower River Shannon Special Area of Conservation (SAC) incorporates the estuary and is 120 km (75 mi) in length, running from Killaloe to Loop Head. The Shannon has a high tidal range, up to around 5.44 m (17.8 ft) at Limerick docks, such that the estuary has been considered for tidal power schemes, despite occasionally experiencing a tidal bore.

The Barrow (Irish: An Bhearú) is a river in Ireland. It is one of The Three Sisters, the other two being the River Suir and the River Nore. The Barrow is the longest of the three rivers and, at 192 km (120 mi), the second-longest river in Ireland, behind the River Shannon. The catchment area of the River Barrow is 3,067 km before the River Nore joins it a little over 20 km before its mouth. The river's long term average flow rate, again before it is joined by River Nore, is 37.4 cubic metres per second. At the merger with the River Nore, its catchment area is ca. 5,500 km and its discharge over 80 m/s.