Naperville features a relatively flat to gently rolling topography, a direct result of the Wisconsin glaciation that flattened much of the Midwest during the last Ice Age. The average elevation is around 715 feet (218 meters) above sea level.
The most notable topographical variations occur along the banks and floodplains of the DuPage River. Here, the land dips gently to form the river valley, creating scenic bluffs and low-lying wetlands. While there are no mountains or high plateaus, the gentle moraines left behind by retreating glaciers provide subtle hills, particularly in the southern and western portions of the city. Because of the flat terrain and proximity to the river, some low-lying areas are designated as flood plains, which the city manages through an extensive system of retention ponds and green spaces.