Tunxis State Forest is approximately 9,152 acres divided into sections on both sides of the Barkhamsted Reservoir. It contains large areas of unbroken forest in the towns of Hartland, Barkhamsted, and Granby. Even at the time of the original purchases for Tunxis in 1923, much of the area was already heavily forested. This is unlike many other parts of the state that, back then, were only gradually growing into forest from farm abandonment. Today, Tunxis is part of a large area of wildland that includes adjacent property of the MDC (Metropolitan District Commission, which is a major drinking water supplier), other Connecticut state forests, and Granville State Forest in Massachusetts.

Many types of wildlife can be seen at Tunxis. Near the end of the Twentieth Century, the area was one of the earliest in the state to see moose and black bear. It is a "working forest", actively managed for improved forest health and diversity, and to produce forest products. It is also a popular forest recreational "escape" for enthusiasts who like to hike, cross-country ski, snowshoe and hunt