Bordering both Connecticut and Rhode Island, this popular 4,640-acre state forest offers a variety of recreational opportunities. Visitors can enjoy swimming, boating and fishing at Wallum Lake and hiking, horseback riding, cross-country skiing and snowmobiling onmiles of woodland trails. Facilities include two boat ramps, a pavilion, bathhouses, swimming beach, interpretive center, picnic area and restrooms. The Midstate Trail, a long-distance hiking trail that extends through central Massachusetts to Mt. Watatic in the north, runs through the forest.

Douglas State Forest also includes a rare example of Atlantic White Ceder swampland. A 5-acre portion of this swamp is designated as a Massachusetts Wildland. It is accessible to the public via a boardwalk trail.