GR 122 is one of the less known long-distance trails, certainly in Flanders. That probably has to do with the all but spectacular profile of this path.

The trail starts in the small town of Hulst, situated in the Netherlands, just across the belgian border. The path soon enters Belgium and then runs through the provinces of Oost-Vlaanderen and Hainaut. Passed Tournai the trail leaves Belgium again and continues through France in a southeastern direction. The path more or less follows the border with Belgium. It ends in the french Champagne-Ardenne region where it joins the more popular GR 12 trail.

The Belgian part between Hulst and Tournai is described in a topoguide written in Dutch.
We're not aware yet of publications covering the French part of the trail, but we've seen French IGN maps where the trail was drawn on the map.

Below is the link to the description of the topoguide covering the Hulst - Tournai part.