Irish Sea

Irish Sea
Irish Sea satellite image.jpg
Satellite image
Irish Sea – relief, ports, limits.tif
Limits and ports: ferry port / freight only
LocationBritish Isles
Coordinates53°N 5°W / 53°N 5°W / 53; -5109 acre⋅ft)
IslandsAnglesey and Holy Island, Isle of Man and Calf of Man, Bardsey Island, Walney, Lambay, Ireland's Eye
Settlements(see below)
Location of the Irish Sea
From the pier at Dún Laoghaire
a suburban seaside town in County Dublin, Ireland

The Irish Sea (Irish: Muir Éireann / An Mhuir Mheann,[1] Manx: Y Keayn Yernagh,[2] Scots: Erse Sie, Scottish Gaelic: Muir Èireann,[3] Ulster-Scots: Airish Sea, Welsh: Môr Iwerddon, Cornish: Mor Iwerdhon) separates the islands of Ireland and Great Britain; linked to the Celtic Sea in the south by St George's Channel, and to the Inner Seas off the West Coast of Scotland[4] in the north by the North Channel, also known as the Straits of Moyle. The countries that are on its shoreline are, Scotland on the north, England on the east, Wales on the southeast, Northern Ireland and the Republic of Ireland on the west.

The Irish Sea is of significant economic importance to regional trade, shipping and transport, as well as fishing and power generation in the form of wind power and nuclear power plants. Annual traffic between Great Britain and Ireland amounts to over 12 million passengers and 17 million tonnes (17,000,000 long tons; 19,000,000 short tons) of traded goods.

Anglesey, Wales, is the largest island in the Irish Sea, followed by the Isle of Man. Manx Sea is occasionally, but rarely, in use.(Irish: Muir Meann,[5] Manx: Mooir Vannin, Scottish Gaelic: Muir Mhanainn).[6][7][8]


The Irish Sea is connected to the North Atlantic at both its northern and southern ends. To the north, the connection is through the North Channel between Scotland and Northern Ireland and the Malin Sea. The southern end is linked to the Atlantic through the St George's Channel between Ireland and Pembrokeshire, and the Celtic Sea. It is composed of a deeper channel about 190 miles (310 km) long and 20–30 miles (32–48 km) wide on its western side and shallower bays to the east. The western channel's depth ranges from 80 metres (260 ft) up to 275 m (902 ft) in the Beaufort's Dyke in the North Channel.

Cardigan Bay in the south, and the waters to the east of the Isle of Man, are less than 50 m (160 ft) deep. With a total water volume of 2,430 km3 (580 cu mi) and a surface area of 47,000 km2 (18,000 sq mi), 80% is to the west of the Isle of Man. The largest sandbanks are the Bahama and King William Banks to the east and north of the Isle of Man and the Kish Bank, Codling Bank, Arklow Bank and Blackwater Bank near the coast of Ireland. The Irish Sea, at its greatest width, is 120 miles (190 km) and narrows to 47 miles (76 km).[9]

The International Hydrographic Organization defines the limits of the Irish Sea (with St George's Channel) as follows,

On the North. The Southern limit of the Inner Seas off the West Coast of Scotland, defined as a line joining the South extreme of the Mull of Galloway (54°38'N) in Scotland and Ballyquintin Point (54°20'N) in Northern Ireland.
On the South. A line joining St. David's Head in Wales (51°54′N 5°19′W / 51°54′N 5°19′W / 51.900; -5.317) to Carnsore Point in Ireland (52°10′N 6°22′W / 52°10′N 6°22′W / 52.167; -6.367).[4]

The Irish Sea has undergone a series of dramatic changes over the last 20,000 years as the last glacial period ended and was replaced by warmer conditions. At the height of the glaciation, the central part of the modern sea was probably a long freshwater lake. As the ice retreated 10,000 years ago, the lake reconnected to the sea.