Europe is constructing the world’s longest underwater tunnel, the Fehmarn Belt Tunnel, which will connect Denmark and Germany ...

Linking Denmark and Germany, the Fehmarnbelt will carry two-lane road highways under the water in both directions, plus two electrified rail lines — a multiple tube thoroughfare that will plunge ...

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.