What are some unique features of Onondaga Cave State Park near Sullivan?

Onondaga Cave State Park is like a twin to Meramec State Park, offering more riverside landscapes and an underground marvel to explore. Onondaga Cave is a National Natural Landmark, offering guided tours of the massive stalagmites and stalactites. Above ground, head up to the bluffs for panoramic river views. The year-round campground offers a mix of shaded basic and water/electric sites, with some close to the waters.