From Shetland to the Western Isles, campaigners argue ageing ferries are driving depopulation – and undersea tunnels are the only 21st-century solution

For Alec Priest, an instrument technician at Sullom Voe oil terminal on Shetland, the case for digging tunnels under the narrow stretches of ocean that separate his home from work is clear-cut.

As things stand, two ageing ferries crossing tidal sounds notorious for their powerful currents break up his commute. For a casual tourist, that adds to the mystique. For time-pressed islanders, care workers and businesses, it adds delays, stress and costs.

Those two ferries over Bluemull and Yell Sound convert a 34-mile drive from Priest’s home at Baltasound on Unst, the most northerly of Shetland’s islands, to Sullom Voe on Shetland’s main island, into a 3.5 hour round trip. He works 12-hour shifts at the terminal.

“It’s a colossal waste of time,” he said. “During the winter, if you have any gales, there’s a good chance the ferries will stop. It does make you cautious.”