Oudsberg

Oudsberg is the largest and highest inland drift dune in Flanders, tucked into the forests near Gruitrode in the municipality of Oudsbergen, in the Belgian province of Limburg. Also known locally as Zandberg, this sandy summit forms the heart of a dune belt that once stretched from Hechtel all the way to Maaseik — a landscape shaped by wind carrying sand from the Meuse river valley back in the Pleistocene.

What makes this dune stand out?

Today Oudsberg rises to roughly 85 meters above sea level, though historically it reached as high as 95 meters, making it one of the tallest elevations in Limburg. Over recent decades the summit has lost at least 7 meters in height — a natural process of erosion and sand movement typical of living, shifting inland dunes. This ongoing dynamic is exactly what keeps Oudsberg classified as an open drift dune, unlike many other, long-since-stabilized and forested elevations in the region.

What can visitors find in the reserve?

Since 1998, Oudsberg has held official status as a Flemish nature reserve, covering an area of about 223 hectares. Within its boundaries, sandy dunes alternate with sweeping heathland, stately forest stands, and butterfly-rich heather grassland. This mix of habitats gives the site both scenic and ecological value, which is why it also carries European-level protection as part of the Natura 2000 network.

How does Oudsberg fit into the wider landscape?

The dune forms part of the so-called Duinengordel (dune belt) and lies within National Park Hoge Kempen, Belgium's largest national park. The surrounding Gruitroderbos forest sharpens the contrast between the dark green of the tree cover and the pale, sandy ridge of the dune, making this one of the more distinctive landscape features in the Kempen region.

Can you reach it on foot?

Yes — a hiking trail connects Gruitrode with the reserve, forming part of the larger trail network of National Park Hoge Kempen. The main loop route in the area covers about 14.6 km with roughly 213 meters of elevation gain, a noticeable challenge given that most of Limburg is otherwise flat terrain — largely due to the repeated climbs over dune ridges along the way.

Where does the name of the municipality Oudsbergen come from?

The dune's name, Oudsberg, gave rise to the name of the entire municipality of Oudsbergen, formed on 1 January 2019 from the merger of the former municipalities of Opglabbeek and Meeuwen-Gruitrode. It's a rare case of a local natural feature — an unassuming forest dune — lending its name to an administrative unit that today counts nearly 24,000 residents.

Frequently asked questions

Is Oudsberg a natural dune or a man-made mound? It is a natural inland dune, formed by wind carrying sand from the Meuse valley during the Pleistocene, not the result of human construction.

Can you walk to the top of the dune? Yes, the reserve is accessible on foot via marked trails, including a route connecting Gruitrode to Oudsberg as part of the National Park Hoge Kempen trail network.

Why is the dune shrinking? Sand is gradually moved by wind and erosion, a natural process for open, unstabilized dunes, which has caused the summit to lose at least 7 meters compared to its historical maximum height.