Construction for the world's longest immersed tunnel is underway.

Slated to open to the public in 2029, the Fehmarnbelt Tunnel will connect the 11.1 miles of Baltic Sea between Denmark and Germany.

Connecting the German island of Fehmarn and the Danish island of Lolland across the Fehmarn Belt, it will be the longest combined road and rail tunnel in the world.

"Today, if you were to take a train trip from Copenhagen to Hamburg, it would take you around four and a half hours," Jens Ole Kaslund, technical director at Femern A/S, the state-owned Danish company in charge of the project, told CNN on Monday. "When the tunnel will be completed, the same journey will take two and a half hours.”

For those journeying between the two cities by car, the trip will be about an hour shorter. Taking a ferry across the strait takes about 45 minutes now. When the tunnel is built, travel across will take seven minutes by train (traveling about 125 miles per hour) and 10 minutes by car (traveling about 70 miles per hour).

Funding for the Fehmarnbelt Tunnel will be generated by fees to use it when it opens.

It will take approximately 3,000 people to build the tunnel over a length of about eight and a half years and will sit more than 40 meters beneath the Baltic Sea and require an amount of steel, equivalent to about 50 Eiffel Towers, CNN noted.

For those curious to watch the construction process, a livestream began on YouTube on Oct. 12.

Construction began with a new harbor in Lolland. By early 2021, workers will begin building a factory on the island. Construction of the tunnel itself will not begin until 2023.

The tunnel has been allotted a budget of about $8.2 billion, a significantly smaller cost than what it took to build the Channel Tunnel, connecting England to France. When the “Chunnel” opened in 1993, it cost approximately $15.5 billion to construct its 30 miles.