Europe’s undersea mega-tunnel will transform travel between Denmark and Germany

A journey that currently involves a ferry crossing, weather checks and a wait at the port could soon take little more than the length of a coffee break.

Engineers have successfully installed the first section of the Fehmarnbelt Tunnel, an 18-kilometre undersea link that will connect Denmark and Germany beneath the Baltic Sea. Once complete, the crossing between Rødbyhavn in Denmark and Puttgarden in Germany is expected to take just seven minutes by train and around 10 minutes by car, replacing a ferry journey that currently lasts about 45 minutes.

The project has been years in the making and is one of the largest infrastructure schemes underway in Europe. It is also set to become the world's longest immersed tunnel, a type of tunnel built from prefabricated sections that are lowered into a trench on the seabed and joined together underwater.

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The scale of the engineering is difficult to overstate. The finished tunnel will consist of 89 concrete elements, each built at a dedicated facility in Rødbyhavn. Standard sections measure 217 metres in length and weigh more than 73,000 tonnes before being floated out to sea and carefully positioned on the seabed.

The successful installation of the first tunnel element marks an important shift in the project. Construction is no longer confined to factories and harbour facilities; the tunnel itself is now beginning to take shape beneath the Baltic.

For travellers, the appeal is obvious. The fixed link will eliminate dependence on ferry schedules and create a faster route between Scandinavia and mainland Europe. Rail passengers are expected to benefit particularly strongly.

Journey times between Copenhagen and Hamburg could eventually fall from around four-and-a-half hours to roughly two-and-a-half hours once related railway upgrades are completed.

The tunnel's significance extends beyond tourism. It forms part of a key European transport corridor linking Scandinavia with Central and Southern Europe, and is expected to make the movement of both passengers and freight more efficient. Supporters of the project say it could encourage a greater shift towards rail transport, helping reduce congestion and emissions on some long-distance routes.

Not everything has gone entirely to schedule. Authorities have confirmed that the tunnel is likely to open in phases, with the road connection expected to enter service before the railway. Environmental approvals and construction-related challenges have contributed to adjustments in the timeline.

Even so, the project has now reached a stage where its ambitions are becoming visible. Beneath the Baltic Sea, the first piece of what will become one of Europe's most important transport links is already in place.

If construction continues as planned, travellers heading between Denmark and Germany may soon find that one of northern Europe's most familiar ferry crossings has become a journey underground.