The tunnel will connect the districts of Randaberg and Bokn, which are separated by a 16-mile body of water, cutting the 21-hour journey across the country in half.

Dubbed as the Rogfast tunnel, it will connect the city of Stavanger in the south, to the northern city of Bergen. It will also link half a dozen cities across the Scandinavian country.

Currently, residents have to take multiple ferries in waterways busy with shipping vessels and cruise liners - at seven points along the coast.

Norway, which has just 5 million residents, will spend $47 billion (£36 billion) on the mega-project.

Bergen is important for Norway’s fishing industry, while Stavanger is a major North Sea oil centre.

The existing E39 motorway, which remains above ground, will be widened as part of the project.

The country has toyed with other crossing options over the years.

Those include a record-length suspension bridge, or a floating tunnel, anchored to the seabed.