Photo: Sønderborg Kommune

Discover the birdlife at Mjels Sø

Explore Mjels Sø in northern Als, where you can enjoy views across the water and discover a rich variety of birdlife. Look out for kingfishers, which breed around the lake, or keep an eye on the skies for white-tailed eagles, regularly spotted in the area. You may also see flocks of geese and ducks resting on the water.

A walking trail of approximately 2 km follows the northern shore of the lake. Along the way, you can enjoy views across the water, with picnic areas featuring tables and benches at both ends of the trail.

Visit the old pumping station

At the western end of Mjels Sø, you'll find the old pumping station, which was restored in 2017.

Inside, you can explore an exhibition about the area before heading up to the viewing platform to take in the views across the lake and watch the birdlife.

The pumping station also has an indoor seating area where you can take a break during your walk.

The dam between Mjels Sø and Mjels Vig

Did you know that Mjels Sø was once part of an inlet stretching from Als Fjord through Mjels Vig and further inland?

Around 1590, Duke Hans the Younger ordered the construction of two dams. One was built at Mjels Vig, separating the innermost part of the inlet from the sea, while the other was built at Broballe.

These were among the earliest land reclamation projects in Denmark. The dams were fitted with sluices that allowed freshwater to flow out while preventing saltwater from entering. Over time, the former inlet became the freshwater lakes Mjels Sø and Bundsø.

From drained farmland back to a lake

In the mid-19th century, work began to drain the lakes so the land could be used for agriculture. For many years, the former lakebeds were drained and cultivated.

In 2005, Mjels Sø was restored as a lake after more than 100 years of drainage and farming.

Today, Mjels Sø covers approximately 55 hectares and is owned and managed by Aage V. Jensen Naturfond, which also owns the nearby Bundsø.

Can you go boating on Mjels Sø?

Boating is not permitted on Mjels Sø. This also applies to the use of float tubes.

Instead, you can enjoy the lake from the walking trail along its northern shore or from the viewing platform at the old pumping station.

Parking at Mjels Sø

You can park at the old pumping station at Færgevej 7, 6430 Nordborg, or at Skolebakken at the eastern end of the lake.

Camping in tents or similar accommodation is not permitted at Mjels Sø. However, overnight stays are possible at Mjels Vig Bådehavn, which also has a number of shelters.

Last updated on 21 October 2026.