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Norway is drilling 27 kilometers of rock 392 meters below the bottom of a fjord to build the world’s largest and deepest underwater road tunnel — when completed, a 21-hour journey will be reduced to 10.

Written by Douglas Avila
Published on 21/04/2026 at 18:47
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With 27 kilometers in length and a deepest point of 392 meters below sea level, Rogfast will replace seven ferry crossings on the west coast of Norway and cut a 21-hour journey in half

On the west coast of Norway, the E39 highway winds between deep fjords for 1,090 kilometers.

To travel this stretch from Trondheim to Kristiansand, drivers need 21 hours — and rely on seven ferry crossings that stop in bad weather.

The Rogfast project aims to change that by drilling through the rock beneath the fjords.

When completed in 2033, the tunnel will have 27 kilometers in length and reach 392 meters below sea level — the deepest in the world for vehicles.

The crossing that currently depends on ferries will take only 35 minutes by car inside the tunnel.

The estimated cost is US$ 2.4 billion (about 20 billion Norwegian kroner).

Deep Norwegian fjord with cliffs and dark blue water
The fjords of Norway are spectacular but force drivers to rely on ferries that stop in bad weather.

392 meters of rock and water above: how it works

The Rogfast tunnel will pass under the bed of the Boknafjorden fjord, in the Rogaland region.

There will be four lanes — two in each direction.

At the deepest point, the road will be 392 meters below sea level.

In the middle of the tunnel, there is an unprecedented feature: an exit to the island of Kvitsøy, with an underground roundabout at 250 meters depth.

It will be the deepest road roundabout on the planet.

Construction began in 2018, with the first main contract in the fall of 2021.

The project faced a pause in 2019 due to rising costs but has resumed.

Why Norway needs this tunnel

The Norwegian west coast is cut by fjords that act as natural barriers.

Each fjord forces cars and trucks to stop, board ferries, and wait — sometimes for hours on stormy days.

The E39 has seven ferry crossings, making transportation unpredictable and slow.

Rogfast eliminates one of these barriers, connecting Stavanger, Haugesund, and Bergen by continuous land.

The total time for the E39, from 21 hours, will drop to about 10 hours when all projects are completed.

Interior of a road tunnel under construction with drilling equipment
Excavating Rogfast needs to drill 27 km of rock nearly 400 meters deep under the fjord.

Norway is the country of tunnels: Rogfast will be the king

Norway already has the longest road tunnels in the world.

The Laerdal Tunnel, at 24.5 kilometers, is the current world record holder.

The Ryfast, at 14.4 kilometers, holds the record for road depth at 292 meters.

Rogfast will surpass both: it will be 2.5 km longer than the Laerdal and 100 meters deeper than the Ryfast.

The country has more than 1,100 road tunnels — drilling through mountains is part of the Norwegian DNA.

The economic impact: tourism, trade, and jobs

The continuous road connection will accelerate trade and tourism on the west coast.

Businesses that depended on ferry schedules will have logistical predictability.

Tourists will be able to travel the coast without maritime interruptions.

Funding combines tolls and support from the Norwegian government.

For a country that already relies on oil from the North Sea, investing US$ 2.4 billion in transportation infrastructure is a bet on economic diversification.

Ferry crossing Norwegian fjord with mountains in the background
The ferries crossing the Norwegian fjords are picturesque, but make transportation unpredictable and slow.

The challenges of drilling rock 392 meters under water

The engineering of Rogfast faces extreme hydrostatic pressure.

The rock at this depth may have fractures and water seepage from the fjord.

Ventilation for a 27 km road tunnel is complex — vehicle gases need to be continuously extracted.

The underground roundabout for Kvitsøy adds an unprecedented layer of complexity.

The Norwegians have experience: Laerdal, Ryfast, and dozens of other tunnels have proven that the local geology is viable.

But 392 meters is a new record, and every additional meter of depth increases the risks.

What could go wrong

The project has already faced cost increases that caused a pause in 2019.

The budget rose from the estimated €1.9 billion to US$ 2.4 billion.

The completion, initially expected for earlier dates, now points to 2033.

Unpredictable geology under the fjord could cause further delays.

However, Norway has a strong track record of delivering tunnels — even if delayed.

When Rogfast opens, driving along the Norwegian coast will be like traveling on a European highway — only 392 meters under a fjord.

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Douglas Avila

I've been working with technology for over 13 years with a single goal: helping companies grow by using the right technology. I write about artificial intelligence and innovation applied to the energy sector — translating complex technology into practical decisions for those in the middle of the business.

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