A trip to the Fehmarn Belt Tunnel:
Europe’s largest infrastructure project

The Fehmarn Belt Tunnel will soon be the longest immersed tunnel in the world, and you can watch it being built live. From Grömitz, you can reach the construction site in just under 45 minutes. Here you’ll find the key facts about the tunnel, tips for your trip and everything you need to know for a stop-off at aja Grömitz.

As at July 2026

We update this page regularly as soon as there is any news on the progress of the construction work. The latest major development: in May 2026, the first of 89 tunnel segments was lowered into the sea.

What exactly is the Fehmarn Belt Tunnel?

The tunnel connects the German island of Fehmarn with the Danish island of Lolland. It replaces the ferry between Puttgarden and Rødbyhavn, which has been carrying cars and trains across the Baltic Sea since 1963. It is not yet complete. Nevertheless, the construction site is already well worth a visit.

Key facts at a glance:

Route: Puttgarden (Fehmarn) ↔ Rødbyhavn (Denmark)

Length: around 18 kilometres

Construction method: immersed tunnel comprising 89 precast concrete segments, each 217 metres long and 42 metres wide

Tubes: two for cars and lorries, two for trains, with a narrow service corridor in between

Journey time once completed: approx. 10 minutes by car, 7 minutes by train

Start of construction: January 2021 in Denmark, November 2021 in Germany

Planned opening: 2031 (as at July 2026); the full railway line is due to follow in 2032

A look back

How did the Fehmarn Belt Tunnel come about?

The idea is older than one might think. Initial feasibility studies were carried out as early as the 1990s, prompted by a similar project between Denmark and Sweden across the Öresund. On 3 September 2008, Germany and Denmark finally signed the intergovernmental treaty for the Fehmarn Belt fixed link – at that time, a bridge was even still under discussion, but the decision was later made to build a tunnel. Building permission has been in place on the German side since 3 November 2020, and construction has been underway since 2021.

From the aja Grömitz to the tunnel construction site

From the aja Grömitz, it’s around 55 kilometres to Puttgarden on Fehmarn – just under 45 minutes by car via the A1. A perfect day trip for your Fehmarn Belt Tunnel and Baltic Sea holiday.

Right next to the German construction site on Marienleuchter Weg, there has been a viewing platform with binoculars and information boards since 2025 – here you can view the Fehmarn Belt Tunnel without actually entering the construction site. If you’d like to find out more, head to the information centre in Burg on Fehmarn. There, Femern A/S explains how concrete and the seabed are being transformed into a landmark structure that will stand for a century.

An exterior view of the aja Hotel Grömitz, with the Baltic Sea in the background.

A pair of hands is holding cocktails garnished with strawberries.

aja Grömitz

After all that concrete and the smell of building sites, you’ll need to feel the sand beneath your feet again. That’s exactly what the aja Grömitz is for: right in the heart of Grömitz, on the seafront, less than two minutes from the water.

Many rooms with a view of the Baltic Sea

Free access to the Grömitzer Welle: a water park with a sauna, accessible directly via the bathrobe corridor

Fitness area to work up a sweat

Restaurant with sea views, breakfast and evening buffets

Rooftop bar with a roof terrace

aja Offers & Packages
for your holiday in Grömitz

A snow-covered beach with water and buildings in the background.

aja Grömitz

All offers on request and subject to availability. This is a limited contingent, depending on the offer plus single room, seasonal, weekend and public holiday surcharges.

Frequently Asked Questions
on the Fehmarn Belt Tunnel

Where exactly does the Fehmarn Belt Tunnel run?

It links Puttgarden on the German island of Fehmarn with Rødbyhavn on the Danish island of Lolland and lies up to 40 metres below sea level.

How long will the Fehmarn Belt Tunnel be?

At around 18 kilometres, it will be the world’s longest immersed tunnel once it is completed.

When will the Fehmarn Belt Tunnel open?

As at July 2026: Femern A/S is currently planning to open the link in 2031, with the full rail link due to follow in 2032. Earlier deadlines have already been postponed several times.

How much will the Fehmarn Belt Tunnel cost?

Construction costs were estimated at around 7.4 billion euros in 2015. Denmark is covering the bulk of the costs, whilst Germany is primarily funding the road and rail links.

Is it possible to visit the Fehmarn Belt Tunnel construction site?

Yes, on the German side there is the viewing platform on Marienleuchter Weg in Puttgarden and the information centre in Burg on Fehmarn, whilst on the Danish side there is the ‘Pilen’ viewing platform near Rødbyhavn.

Is the ferry between Puttgarden and Rødbyhavn still running?

Yes, Scandlines will continue to take you across the Belt throughout the construction period.

Why is a submerged tunnel being built across the Belt rather than a bridge?

After years of consideration, the decision was made in favour of the immersed tunnel. One reason for this is that it does not disrupt shipping traffic in the Belt.

Is the Fehmarnsund Bridge the same as the Fehmarn Belt Tunnel?

No. The Fehmarnsund Bridge connects the German mainland with the island of Fehmarn, whilst the Fehmarn Belt Tunnel connects Fehmarn with Denmark. Both are currently being supplemented or replaced by new structures.

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