The Irish Sea (Irish: Muir Éireann or Muir Meann; Scottish Gaelic: Muir Eireann Welsh: Môr Iwerddon, Manx: Mooir Vannin) separates the islands of Ireland and Great Britain. It is connected to the Celtic Sea portion of the Atlantic Ocean by St George's Channel between the Republic of Ireland and Wales, and to the north by the North Channel between Northern Ireland and Scotland which forms part of the IHO-designated 'Inner Seas off the West Coast of Scotland' marine area. The Isle of Man lies in the middle of the Irish Sea. 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. There has been long discussion of building an 80 km (50 mile) rail tunnel to link Britain and Ireland; annual traffic between the two islands amounts to over 12 million passengers and 17 million tonnes of trade.