The Upper Natural Bridge of Calaveras County Professional Review and Guide
"One of the wonders of the Gold Country, this remarkable cave on Coyote Creek cuts clear through a limestone ridge, permitting people to swim or wade through the heart of the hillside. Even if you don’t want to get wet, the sight alone is worth the walk.
The extensive karst region of Calaveras County, in the Sierra foothills, is famed for its commercially operated caves, of which Moaning Caverns is the closest to our hike. Although highly celebrated among nineteenth-century tourists, the Natural Bridges today are visited mostly by locals, who enjoy floating through them on inflated inner tubes or air mattresses. Freely accessible to the public, the Natural Bridges are managed by rangers from New Melones Reservoir, though local people also keep an eye out for vandals."