The forests and waters of the Cumberlands are among the most biologically rich temperate-zone systems in the world, harboring an extraordinary number of plants, fish, mussels, salamanders, fungi, and other species, many of which occur only in the Cumberlands, but nowhere else.

The Cumberlands also contains thousands of caves that support one of the most diverse assemblages of cave animals on earth. The biological importance of the Cumberlands is largely due to the unique geology of the region. Formed from the remnants of an ancient sea, the area is made of a low mountain chain (3,000-4,000 feet elevation) that is surrounded by a high plateau (~1,500 feet elevation).

The Plateau is heavily eroded and contains an abundance of deep river canyons. Some of these river canyons, know as largely as "gulfs"--are nearly one thousand feet deep and contain a vast array of habitats that support an abundance of life forms.