Fehmarnbelt Tunnel would be the world’s longest immersed tunnel

Fehmarnbelt Tunnel will be the world's longest immersed tunnel

Editor’s Note — Monthly Ticket is a CNN Travel series that spotlights some of the most fascinating topics in the travel world. September’s theme is ‘Build it Big,’ as we share the stories behind some of the world’s most impressive feats of engineering.

(CNN) — Descending up to 40 meters beneath the Baltic Sea, the world’s longest immersed tunnel will link Denmark and Germany, slashing journey times between the two countries when it opens in 2029.

After more than a decade of planning, construction started on the Fehmarnbelt Tunnel in 2020 and in the months since a temporary harbor has been completed on the Danish side. It will host the factory that will soon build the 89 massive concrete sections that will make up the tunnel.

“The expectation is that the first production line will be ready around the end of the year, or beginning of next year,” said Henrik Vincentsen, CEO of Femern A/S, the state-owned Danish company in charge of the project. “By the beginning of 2024 we have to…