While on board the MV Loch Seaforth last week, Mr Yousaf was quizzed about whether he could ever see tunnels being introduced as an alternative to ferries to link different islands.

The First Minister said the Scottish Government was open to it but warned of severe budget constraints as ministers point their focus at new vessels.

He told The National: “We’ve always been open as a government to fixed links.

“It’s a legitimate question, but we‘re discussing this at a time when the UK Government has now cut our capital budget by £1.3 billion.

“So our capital budget is really constrained, but we’re definitely open to conversations about fixed links and a number of island communities are working on feasibility studies.

“There’s other European countries that have done it very well, the Faroe Islands are probably the stand out.

“So we’re always up for that discussion but at the moment we’re putting a lot of our capital infrastructure into the building of new vessels by 2026.”

Last November, a delegation of Scottish MPs travelled to the Faroe Islands to view a 10.2-kilometre route linking the main island of Streymoy with Sandoy to the south, which cost roughly just £9.8 million per km.

Na h-Eileanan an Iar’s Angus MacNeil, who was part of the delegation, said he hoped the trip would point Scottish focus towards the huge benefits of island tunnels, which have cut travel times significantly in the Faroes at a fraction of the cost of HS2.

The Streymoy to Sandoy undersea tunnel is the fourth to open up in the Faroe Islands, with the nation also being famous for the world’s first under-sea roundabout - part of the Eysturoyartunnilin connecting the islands of Streymoy and Eysturoy.

Shetland Islands Council said last September that talks to connect a number of the islands with subsea tunnels were at an “advanced stage”.

Councillors are proposing four tunnels be built: from the Mainland to Yell; Yell to Unst; Mainland to Whalsay; and Mainland to Bressay.

The local authority has just appointed Stantec to deliver a strategy and outline business cases for its Inter-island Transport Connectivity Programme.

In September, the council’s political leader, Emma Macdonald, said that a solution to inter-island travel problems simply has to be found, and soon.

She said: “The importance of the inter-island transport network to life in Shetland cannot be overestimated.

“It is the very definition of a lifeline service and is the social and economic backbone of the islands.”