20km door het Zoniënwoud

20km door het Zoniënwoud is a 20 km forest race in Auderghem, on the edge of Brussels. It is a trail run, with over 90% of the route unpaved. The course is fully marked, and runners receive one aid station. The race carries a UTMB Index 20K listing and features 370 meters of climbing, suitable for those seeking a short, genuine off-road challenge. The route remains primarily within the Zoniënwoud, utilizing gravel paths and single tracks with some steep ascents. It is entirely traffic-free, marked by orange arrows and large signs, and limited to 1,500 participants across four start waves. The event includes a walking option for children up to 12 and dogs, offered free of charge, contributing to a wider local atmosphere compared to a race exclusively for runners.