It’s a bit of a drive from Philadelphia, but it’s our favorite hike, and totally worth it for the geology (especially for us hill and rock challenged South Jersey folks). After a mile hike UP Pyramid Mountain (this is the steepest part of the trail), you come to a spot with several huge glacial erratics (remnants of the last ice age 18,000 years ago). The most impressive is Tripod Rock: gigantic and held up by only 3 small boulders. After the obligatory photo-op, this is a great place for a picnic.
You can return via the reservoir for more rocks and pretty water views.
This isn’t the wilderness – New York City can viewed from the first overlook on a clear day, and high power lines cross the park, but the 4 mile round trip hike is definitely worth the drive.

There is a small visitor center (open 9-4:30)near the parking lot with some nature displays, history of the area, children’s activities, and bathrooms (otherwise, there is a porta-potty in the parking area). They also rent snow shoes for anyone wanting to try a winter adventure.
Tobey says: Pretty!
https://www.morrisparks.net/index.php/parks/pyramid-mountain-natural-historic-area/