An unconventional and first-of-its-kind form of transportation infrastructure could be the answer to traveling across fjord-ridden Norway.

Photo credit: Norwegian Public Roads Administration

To complete the 680-mile drive under current conditions, you would have to allow 21 hours for travel. Why? Traveling north-to-south across the country requires eight ferry trips across fjords. Norway's fjords are too deep and too wide to support bridges. Well, above water ones that is.

A $25-billion project by the Norwegian Public Roads Administration poses a possible solution to that problem: floating underwater tunnels.

The tunnels could cut trip time to 10.5 hours by reducing the need for ferry rides. The project is expected to be completed by 2023. Each tunnel would be suspended under 100 feet of water, held up by pontoons on the fjord's surface and possibly an anchor bolted to the bedrock. Each fjord would be equipped with two tunnels: each two-lane, one for traffic flowing in each direction.

Photo credit: Norwegian Public Roads Administration

Underwater tunnels aren't a new idea for Norway. The country has 1,150 traffic tunnels, 35 of which are located under shallow bodies of water. Fjords, however, can be a mile deep, creating a challenge for conventional tunnels.

The floating underwater tunnels will allow boats to still traverse the fjord without the worry about hitting or being blocked by a bridge.

But there's still a long way to go before floating underwater tunnels become reality. Engineers have several questions to answer, including how wind, waves and currents will affect the structures. If the tunnels prove too difficult, Inhabitat reported, politicians have the right to send the funding to another project.

The following Norwegian Public Roads Administration video offers more information about the project: