Frontenac is one of several provincial parks situated within the Frontenac Axis, the southern arm of the Canadian Shield that extends down into New York state. This geological anomaly is responsible for the land forms in the area that are typically found further north, and for a mix of northern and southern plants and wildlife peculiar to the region. The geology of the park is complex, with several distinct zones. Generally, the park terrain is rugged.

Frontenac is home to many unusual species of bird including eagle, turkey vulture, red-tailed hawk, cliff swallow, loon, osprey, heron, kingbird, kingfisher, warbler, vireo, red-shouldered hawk, wild turkey and ruffled grouse. White tail deer and black bear are common. Coyotes, red fox, fisher, otter, mink, weasel, raccoons and other small mammals abound. Beavers are also abundant. In fact, beaver activities, along with the terrain's poor drainage, are two factors behind the many varieties of wetlands found here.