The Cedarburg Bog is one of the largest and most diverse wetlands in southern Wisconsin. Its 2,200 acres contain deep and shallow bog lakes, submerged and emergent aquatic communities, a small stream, deep and shallow marshes, sedge communities, shrub carrs, swamp hardwoods and large expanses of cedar-tamarack swamp forest. The southernmost string bog in North America lies in the heart of the bog.
String bog is a type of patterned vegetation typically found in the large peatlands of northern Canada. In the Cedarburg Bog over 35 higher plant species and 19 species of breeding birds reach or are near the southern extent of their range in Wisconsin. The pH of the Cedarburg Bog is nearly neutral, a result of the region's calcareous groundwater. Access into the heart of the bog is provided by a boardwalk, and a guidebook to the Bog is available. A quantitative survey of the vegetation in the Cedarburg Bog was completed in 1991.
The uniqueness of the bog has been recognized by its inclusion in the Wisconsin Natural Area System, and it is also registered as a National Natural Landmark by the Department of the Interior. The Cedarburg Bog Natural Area is also an Experimental Ecological Reserve, part of the National EER network.