Sonian Forest Loop (Zoniënwoud)

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Sonian Forest Loop (Zoniënwoud): Brussels’ Beech-Forest Day Hike

Published 17 July 2025 Updated 1 July 2026

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HikeList Score

Sonian Forest Loop (Zoniënwoud) scored 76/100 on HikeList's trail-quality metrics.

Very Good

See score breakdownHide breakdown

Ideal length 55
Balanced challenge 100
Scenery & wildness 98
Varied terrain 52
Accommodation 57
Food & support 68
Path quality 98
Season flexibility 89

Computed from length, challenge, scenery & wildness, terrain variety, accommodation, food & support, path quality and season flexibility.

The Sonian Forest Loop is a representative 16 km day walk through the Zoniënwoud / Forêt de Soignes on the south-eastern edge of Brussels, Belgium. It is a moderate loop on mostly dirt and gravel forest paths, with about 150 m of ascent and no technical terrain. Expect high-canopy beech woodland, ponds, arboretums and signed local paths rather than one single official “Sonian Forest Loop” waymark. It suits hikers wanting a substantial, easy-to-reach forest hike from Brussels.

Route Overview

This is a circular walk assembled from the Sonian Forest’s dense signed path network, not a fixed official trail with one canonical start. Good gateways include Boitsfort/Watermael, Groenendaal, Jezus-Eik, Tervuren and Hoeilaart; trains serve Groenendaal, Boitsfort/Bosvoorde and Boondael, with trams 7, 8, 25, 44 and 92 reaching forest edges. A typical 16 km loop links the beech “cathedral” stands with forest ponds and an arboretum, returning to the same gateway. Use the official forest maps, RouteYou network and local coloured markers. For a longer urban-green route nearby, see the Brussels Green Walk, or link forest walking with the GR 12 Amsterdam to Paris Trail. To explore more of Belgium on foot, the Abbey Trail of Wallonia pairs well for a longer trip south.

History of the Sonian Forest

The Sonian Forest is the largest surviving fragment of the ancient Silva Carbonaria, or Forest of Coal, which once covered much of central Belgium. It was managed and exploited by the Dukes of Brabant and later Spanish and Austrian Habsburg administrations; the long straight avenues, including the Drève de Lorraine, date from Austrian rule in the 18th century. The forest shrank from roughly 10,000 ha around 1800 to about 4,400 ha today, while beech replanting created the high-canopy stands now associated with Zoniënwoud.

Notable highlights

The beech cathedral: Tall European beeches with bare trunks and a closed canopy create long, column-like views through the forest. Autumn is especially distinctive when the leaves turn copper and gold.
UNESCO World Heritage beech stands: Five protected core areas, totalling about 269 ha, are part of the transnational UNESCO beech-forest inscription. They protect rare Atlantic high-beech forest within walking distance of Brussels.
Groenendaal Arboretum: This 13.5-hectare systematic tree collection was laid out for King Leopold II in the late 19th century. Its exotic trees and shrubs make a varied contrast to the surrounding native beech woodland.
Forest ponds: The Koningsvijvers, Gansepootvijver and Boitsfort lakes are quiet rest points for walkers and good places to watch waterbirds and dragonflies. The Boitsfort lakes also overlie a Neolithic site.
Groenendael Priory and Forest Museum: Groenendael is the site of a 14th-century Augustinian priory linked to Jan van Ruusbroec. The nearby Forest Museum explains the woodland’s natural and cultural history.
Wildlife and biodiversity: The forest supports wild boar, roe deer, woodpeckers, buzzards, bats, orchids, fungi and beetles, including stag beetle habitat. Stay on paths and give wildlife space.

Challenges to expect

The walking is not technical: the challenge is distance, navigation and occasional mud. There is no single official 16 km waymark, so follow a map or GPX across the signed path network. Most surfaces are dirt or dolomite gravel, but earth tracks can be muddy after rain, especially off the main paths. The terrain is gently undulating, with some steeper banks in southern sections. Camping and fires are prohibited.

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Ranked #693 of 974

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