The dunes of Fort Mahon mark the transition between the Picardy and the Flemish dune systems, characterised by a small dune ridge. These dunes isolate the eastern part of the Flemish maritime plains from the sea. No more than around 20 metres high and about 200 metres wide, they extend over 3 kilometres. Grassland behind the dunes, interspersed with areas of sea buckthorn, line the trail. A discovery loop has been created around two large pools between the Blériot campsite and the Family Holiday Village (VVF).