At 45m high (148ft) and 36m (118ft) wide, the 1.7km (one mile) long Stad Ship Tunnel will be the only one of its kind – a passage through solid rock able to accommodate 16,000 tonne freight and passenger ships.
Ship canals have long been used to make journeys more direct and safer but the Stad peninsula is a mountainous divide, peaking at 645m, between the Norwegian Sea to the north and the North Sea to the south.
Norway has a reputation as the world-leader in tunnelling. They have already achieved the world’s longest road tunnel.
While it will be the first proper ship tunnel, the engineering behind it will not involve radical innovation.
“It isn’t an unheard of challenge, it involves building a cofferdam [a watertight enclosure] at either end to keep the water out until excavation is complete,” explains Robert Benaim, Fellow of the Royal Academy of Engineering.
Instead of carving out a slice of the landscape for a canal, engineers will drill and blast through the rock at sea level before removing the dams so the sea can flood a 12m (39ft) deep channel for ships to travel in.