Norway is home to more than 1,100 road tunnels. They cut through the mountains and stretch under its deep sea, allowing vehicles a more direct route through the country’s challenging terrain. The Scandinavian country has burrowed thoroughfares for nearly every mode of transportation—except one.

“We build a lot of tunnels, just not for ships” says Terje Andreassen, head of Kystverket, the Norwegian coastal administration. It’s strange when you think about it. Norway has more than 18,000 miles of coastline, punctuated by rugged cliffs that jut into the sea like outstretched fingers. The country's fjords fill the long, slender gaps between the cliffs. These narrow inlets are famed for their beauty, but are a pain for shipping vessels. Traversing the country's coast requires venturing in and out of fjords, which is inefficient; and rough waters on the open ocean occasionally strand boats in an inlet's relatively placid waters. That’s why, for the last two years, Kystverket and the architecture firm Snohetta have plugged away at a proposal to build the world’s first ship tunnel. The recently approved plan calls for a mile-long passageway through the Stadlandet Peninsula in northwestern Norway, and would afford boats a safe and quick alternative to the tumultuous waters separating two major fjords.

Kystverket

The Stad Ship Tunnel is remarkable for its size and design. At 165 feet tall and 188 feet wide, it’s big enough for a 35-million pound ship to pass through. A canal would accommodate taller ships, but Andreassan says building one would be impossible. The mountain through which the tunnel will run rises more than 1,100 feet into the air. To dig a tunnel, workers will have to remove nearly 18-billion pounds of rock; constructing a canal—what is essentially a tunnel without a roof—would require crews to remove far more.

Construction will begin at opposite sides of the mountain, where workers will drill horizontally through solid rock until they meet in the middle. Once the top of the tunnel is hollowed out, they'll reinforce the arch by applying concrete sprayed with a hose. From there workers will build service routes to transport excavated sediment from the top of the tunnel to the sea, where ships will dispose of the rock.

Kystverket

With the service routes established and the roof secured, workers will resume drilling and blasting through the mountain in horizontal segments, removing chunks of rock up to 44,000 pounds apiece. “You basically have to dig five tunnels on top of each other,” says Snohetta architect Hans Martin Frostad Halleraker. At the end of the process, workers will remove the nine-foot stone thresholds that prevented the sea from entering the tunnel during construction, flooding the tunnel with 36 feet of water.

The construction process is necessarily invasive. “A tunnel like this creates a big scar on the landscape,” Halleraker says. But Snohetta’s design strives to blend the tunnel into the surrounding terrain. The structure's exterior features terraces, which echo the terraced farming techniques the local farmers use to keep soil in place and prevent landslides. Meanwhile, both ends of the tunnel are flanked by concrete blocks and rubber rudders that can withstand the impact of a 16,000 tonne boat moving at five knots.

The concept of fjord-spanning tunnels in Norway goes way back. Plans for a similar passageway existed as early as the late 19th century, when fishermen sought a way to protect their small boats from the region’s notoriously harsh waves as they sailed around the cape. During World War II, the Germans explored building a tunnel in the same location, to expedite the trip from Bergen to Alesund. “The war didn’t last long enough to build it,” Andreassen says. Since then, various groups have proposed some version of Kystverket's plan. Each time, parliament has shut it down before construction could begin. "Political will was missing,"Andreassen says. "The focus has been on roads."

Kystverket

Kystverket estimates the new scheme will cost the government around $314 million dollars to build—a big chunk of money that some experts believe could provide little payoff. “The cost-benefit analysis is negative,” says Knut Samset, a professor of project management at the Norwegian University of Science and Technology who's studied the economics of the tunnel proposal for years. “It’s a very expensive thing.” Weather permitting, it's as fast to sail around the cape it is to sail into the fjord and through the tunnel. Plus, today's boats are big enough and safe enough to handle the choppy waters, which makes traveling through the tunnel a moot point, Knut says. "The idea becomes less relevant the bigger the tunnel gets."

Andreassen disagrees. "The advantage is in bad weather conditions, during which you will save a lot of time and fuel," he says. The tunnel, he says, which will have a capacity of 100 ships per day, will help make sea travel more predictable by alleviating backed up boat traffic caused by the region's regular bad weather. Plus, Andreassen adds, with the right design, the tunnel could become one of Norway's signature tourist spots. Norway's government just announced it included the tunnel plan on its national transport plan. This doesn't mean it's a done deal, but it does mean the world is one step closer to finally getting its first ship tunnel.