River Lagan in the context of "Magheralin"

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.

Belfast (/ˈbɛlfæst/ , BEL-fast, /-fɑːst/, -⁠fahst; from Irish: Béal Feirste [bʲeːlˠ ˈfʲɛɾˠ(ə)ʃtʲə]) is the capital city and principal port of Northern Ireland, standing on the banks of the River Lagan and connected to the open sea through Belfast Lough and the North Channel. It is the second-largest city in Ireland (after Dublin), with an estimated population of 352,390 in 2024, and its metropolitan area has a population of 671,559.

Occupied since at least the Bronze Age, it was chartered as an English settlement in 1613. The town's early growth thereafter was driven by an influx of Scottish Presbyterians. Their descendants' disaffection with Ireland's Anglican establishment contributed to the rebellion of 1798, and to the union with Great Britain in 1800—later regarded as a key to the town's industrial transformation. When granted city status in 1888, Belfast was the world's largest centre of linen manufacture, and by the 1900s her shipyards were building up to a quarter of total United Kingdom tonnage.

Lisburn (/ˈlɪzbɜːrn, ˈlɪsbɜːrn/ LIZ-burn, LISS-burn; Irish: Lios na gCearrbhach [ˌl̠ʲɪsˠ n̪ˠə ˈɟaːɾˠ(ə)wəx] ) is a city in Northern Ireland. It is 8 mi (13 km) southwest of Belfast city centre, on the River Lagan, which forms the boundary between County Antrim and County Down. First laid out in the 17th century by English and Welsh settlers, with the arrival of French Huguenots in the 18th century, the town developed as a global centre of the linen industry.

In 2002, as part of Queen Elizabeth's Golden Jubilee celebrations, the predominantly unionist borough was granted city status alongside the largely nationalist town of Newry. With a population of 45,370 in the 2011 Census, Lisburn was the third-largest city in Northern Ireland. In the 2016 reform of local government in Northern Ireland Lisburn was joined with the greater part of Castlereagh to form the Lisburn City and Castlereagh District.

Belfast Lough is a large sea inlet on the east coast of Northern Ireland. At its head is the city and port of Belfast, which sits at the mouth of the River Lagan. The lough opens into the North Channel and connects Belfast to the Irish Sea.

Belfast Lough is a long, wide and deep expanse of water, virtually free of strong tides. The inner part of the lough comprises a series of mudflats and lagoons. The outer lough is restricted to mainly rocky shores with some small sandy bays. The outer boundary of the lough is a line joining Orlock Point and Blackhead.

Dromara (from Irish Droim mBearach, meaning 'ridge of heifers') is a village, townland (of 242 acres) and civil parish in County Down, Northern Ireland. It lies 10 kilometres (6.2 mi) to the southwest of Ballynahinch on the northern slopes of Slieve Croob, with the River Lagan flowing through it. It is situated in Dromara (civil parish) and the historic barony of Iveagh Lower, Lower Half. In the 2021 census it had a population of 1,118 people.

Donaghcloney or Donacloney (from Irish Domhnach Cluana, meaning 'church of the meadow') is a village, townland (of 300 acres) and civil parish in County Down, Northern Ireland. It lies on the River Lagan between Lurgan and Dromore. In the 2021 census the village had a population of 1,977. It is colloquially referred to as "The 'Cloney" by locals.

The Carryduff River (Irish Abhainn Cheathrú Aodha Dhuibh) is a minor river in County Down, Northern Ireland. It is a direct tributary of the River Lagan and is not navigable.

54°37′30″N 5°58′52″W / 54.625°N 5.981°W / 54.625; -5.981

The River Farset (An Fhearsaid or Abhainn na Feirste in Irish) is a river in Belfast, Northern Ireland. It is a late tributary of the River Lagan.