Jenny Jump State Forest

Jenny Jump State Forest is a protected woodland of approximately 4,466 acres in Warren County that stretches along a mountain ridge with rocky slopes and glacial boulders scattered throughout. The terrain features elevation changes that create varied landscapes across the property.

The forest area contains traces from the Wisconsin glaciation period roughly 21,000 years ago, when thick ice sheets from Canada shaped the landscape and left behind the rocky terrain we see today. These glacial influences are visible in the stone formations found throughout the property.

The Greenwood Observatory, built in 1995 by the United Astronomy Clubs of New Jersey, hosts public stargazing sessions throughout the year. Visitors can observe the night sky and learn about astronomy in a setting dedicated to these activities.

The forest has 14 trails for hiking, 22 camping spots, and several shelters where visitors can stay overnight or rest during the day. Ghost Lake is available for fishing while Mountain Lake is suitable for swimming.

The forest sits in one of the darkest zones in New Jersey, making the night sky far more visible than in most surrounding areas. This quality draws photographers and astronomers seeking to capture and study the stars without light interference.

Location: New Jersey

Inception: 1931

Website: http://state.nj.us/dep/parksandforests/parks/jennyjump.html

GPS coordinates: 40.92203,-74.92558

Latest update: December 8, 2025 19:55