A 21-mile bridge spanning the North Channel of the Irish Sea - from Galloway to Northern Ireland - has been proposed by a think tank (link below.)
http://news.bbc.co.uk/1/hi/scotland/south_of_scotland/6958191.stm The Centre for Cross Border Studies believes the bridge could provide international rail links and ease the strain on air services.
Group director Andy Pollak admitted it would be a massive engineering challenge and would cost about £3.5bn.
However , he claimed the gains could well outweigh the costs.
The lobby group said the scheme could use either a tunnel or bridge to link the two countries.
It would see trains originating in Dublin travelling through Belfast across to Stranraer and then to Glasgow before heading down through Britain and across the English channel.
A similar size project , at 22.5 miles across , is the road bridge being built between Shanghai and Ningbo in east China.