Stony Brook State Park's terrain comprises hilly woodlands, a deep gorge with rugged cliffs overlooking three waterfalls and fascinating rock formations. 125 tent and trailer campsites are scattered in the woodlands above the gorge in the upper or south end of the park. Visitors can hike rim, gorge or nature trails, play tennis on park courts, picnic or swim in either of two stream-fed pools. In winter, three miles of cross-country trails are available for skiers. Some winter hiking is allowed, but not on the gorge trails.

Stony Brook Glen is a new valley in an ancient landscape; a "post-glacial" stream. Since the end of the Ice Age it has eroded a gorge in the soft shale of the hillside creating high cliffs and waterfalls. The rocks of the gorge are older than the dinosaurs and represent compressed sediments which accumulated in an ancient sea. Fossils are occasionally found.

Large, stone and concrete footings cross the gorge from rim to rim near the upper park. They are what remains of two high railroad bridges which supported trains bringing visitors to the park. The Stony Brook railroad station was located where the campground office is today.

During the 1930s, Stony Brook State Park became a bustling center of activity. Federal public works employment programs, including the Civilian Conservation Corps and the Works Progress Administration, put many depression-era unemployed youth to work improving park trails and facilities.

From an original size of 250 acres in the 1920s, Stony Brook has been expanded to 577 acres. For over a century, visitors have been traveling to Stony Brook to experience its gentle, rugged beauty.