LESS than ten miles long and costing about £100 million, a tunnel taking drivers under the sea to Orkney is increasingly being seen as a realistic possibility.
The idea took a small but significant step towards reality yesterday when a Norwegian tunnelling expert outlined a vision of a crossing beneath the Pentland Firth connecting the islands to the Scottish mainland.
Councillors from both sides now look likely to investigate whether a 9.3-mile tunnel would be more cost effective than the hour-long ferry service between Orkney and Caithness which is subsidised by the Scottish Executive.
It is estimated that in 20 years it will cost about 50 million to replace the Hamnavoe, the NorthLink Ferries vessel that sails between Stromness and Scrabster.
Captain Bob Sclater, Orkney Islands Council’s transportation chairman, said: "It seems to be the way ahead. It would mean people could come and go whenever they wanted, with no restriction on travel.
"From what we’ve been told, a tunnel from Orkney to the Scottish mainland would be a feasible option."
John Green, who represents north-east Caithness on Highland Council, said: "When you consider that around 11 million a year in subsidy goes into the Pentland Firth route - it wouldn’t take long to recoup that by building a tunnel."
It was thought a sub-sea tunnel linking South Ronaldsay in Orkney to a point close to John o’ Groats, would cost at least 150 million.
But Eivind Grv, a senior consultant with the Norwegian civil and environmental engineering specialist SINTEF, predicted construction costs of about 6 million a kilometre and a total bill of about 100 million.