Located in southwestern Pocahontas County in the Monongahela National Forest, the Cranberry Glades are an island of northern muskeg in the Southern Appalachians. Several northern plants, animals, and birds reach their southernmost limit here. There are other glade areas in West Virginia, such as Cranesville Swamp, parts of Canaan Valley, and Droop Mountain Bog, but Cranberry is best known due to its large size.

The glades include 1,000 acres and occupy a high valley hemmed in by Cranberry Mountain on the east and south, Kennison Mountain on the west, and Black Mountain to the north. Cranberry River passes through the glades and exits through a narrow water gap between Kennison and Black mountains. Here it passes over erosion-resistant sandstone, which has not allowed the river to cut a deep channel, thus slowing the rate of flow. This accounts for the poor drainage and unique environment of the glades.

The Brooks family of French Creek, Fred, A. B., and later Maurice, were the first naturalists to study this area. Their annual trips, beginning in 1898, usually included a week or two of tenting, long days of collecting plants, birding, and trapping rodents, followed by evenings sorting and identifying specimens by lantern. They published numerous papers on the Glades in scientific journals, which attracted other naturalists to visit.

The glades lie at 3,300 to 3,400 feet above sea level. They consist of open spaces, alder thickets, and bog forests. Dense thickets of speckled alder separate the five openings or glades, which collectively occupy about 100 acres. Around the edges are bog forests made up of red spruce and various hardwoods.

The 10-acre Flag Glade is most accessible. A boardwalk allows visitors to see a cross section of the different ecological conditions and many of the unique plants, birds, and small animals. The largest is Big Glade (59 acres) where two rare plants, bog rosemary and buckbean, occur. Round and Long glades are both ten acres in size. The smallest open area is Little Glade (one acre).

Much of the glades is covered by sphagnum moss, bird-wheat moss, and reindeer moss. These form hummocks up to three feet high. Growing over these are prostrate cranberry vines. Several species of orchids and insectivorous plants occur. Birds reaching their southern breeding range limit here are Swainson's and hermit thrushes, Nashville and mourning warblers, and purple finches.

The glades have been designated as the Cranberry Glades Botanical Area.