Den Dotter is a 205 hectare nature reserve in the sub-municipalities of Aaigem (municipality Erpe-Mere) and Heldergem (municipality Haaltert) in the East Flemish Denderstreek. It's a swampy, almost uninhabited area, with the central brook (beek) Molenbeek-Ter Erpenbeek, named for its numerous mills (molens).The Dotter is crossed by several hiking and cycleways, the hiking path "Den Dotter" starts at the Church of Aaigem.