Relief map of the Irish Sea. The North Channel lies to the north of the Irish Sea, and the St George's Channel to the south. (Major ports shown as red dots. Freight-only ports as blue dots)
Unionist Northern Irish political leaders for decades lobbied the UK government to construct a rail-link tunnel under the North Channel, to better integrate Northern Ireland into the rest of the United Kingdom. In August 2007 the Centre for Cross-Border Studies proposed the construction of a 34 km (21 mi) long railbridge or tunnel, estimating that it may cost approximately £3.5bn.1