The Irish Sea (Irish: Muir Éireann, Manx: Y Keayn Yernagh, Scots: Erse Sea, Scottish Gaelic: Muir Èireann, Ulster-Scots: Airish Sea, Welsh: Môr Iwerddon) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea in the south by St George's Channel, and to the Atlantic Ocean in the north by the North Channel. Anglesey is the largest island within the Irish Sea, followed by the Isle of Man. The sea is occasionally, but rarely, referred to as the Manx Sea (Irish: Muir Meann, Manx: Mooir Vannin, Scottish Gaelic: Muir Mhanainn).
The sea is of significant economic importance to regional trade, shipping and transport, fishing, and power generation in the form of wind power and nuclear plants. Annual traffic between Great Britain and Ireland amounts to over 12 million passengers and 17 million tonnes of traded goods.
The International Hydrographic Organization defines the limits of the Irish Sea (with St George's Channel) as follows: