Ambitious plans to build a tunnel from Orkney to the mainland are being examined by island councillors.
An underwater tunnel built in Norway has proved a huge success
The link, costing more than £100m, could replace a one-hour ferry trip with a 10-minute road journey.
Critics have described the suggested link between South Ronaldsay and John O'Groats, which would take a long time to complete, as "pie in the sky".
Fears have also been voiced that it would jeopardise about 50 jobs provided by the ferry service.
Plans have also been put forward for linking some outlying islands, such Shapinsay and Rousay, to the Orkney mainland by tunnel.
More than 20 similar links have been built in Scandinavia over the past two decades.
An engineer involved in tunnelling projects in Norway, Eivind Grov, is pressing the local authority to go ahead with the seven-mile link under the Pentland Firth.
"Building a tunnel between the isles would of course ease access and improve communications between the islands and also as regards the connection to the mainland," he said.
Mr Grov added: "As far as I can see, the rock looks hard and the distances between the shores are pretty short - so it all looks quite positive as far as feasibility is concerned."
Council convener Stephen Hagen believes the proposals would provide a lifeline for fragile communities.
"De-population has become one of the main major issues in the islands now. I think part of that is because of the extra costs of living there," he said.
"Perhaps if we have fixed links it will make it more encouraging for people to go back to their roots, for new industries to get into the islands and make these areas much more economically viable for the future."
More than 20,000 cattle are exported from Orkney each year. Auctioneer Jim Linklater thinks a tunnel would cut high transport costs.
Plans "could provide a lifliene" to remote island communities
He said: "I would hope it would attract more buyers to come to the islands to buy livestock. As for transportation, I'm sure it could be done cheaper and on a more regular basis.
"Instead of waiting for just one ship per week that we have at the present time, we could have a daily service if we want."
The ferries used for the service between Scrabster and Stromness cost about £30m and have to be replaced every 20 years.
A council spokesman said earlier: "Improvements to Orkney's transport system are a key part of the community plan and the council's corporate plan.
"Fixed links have always been seen as a possible way of achieving this aim and therefore further investigation of the practicalities of tunnels is consistent with policy."
Council members visited Norway in May 2004, where 24 sub-sea routes have been constructed through rock.
The budget for those tunnels, set out by specialist firm Sweco Groner, worked out at about £5,000 per metre.