Fodor's Expert Review Black Chasm Cavern National Natural Landmark

Guided 50-minute tours take you past stalactites, stalagmites, and rare formations of delicate helictites in three underground chambers, one of which also contains a lake. Black Chasm isn't the largest cave in the Gold Country, but its crystals dazzle both eye and camera—the Landmark Chamber, the tour's third stop, inspired a scene in the 2003 film The Matrix Reloaded. Outside is an area where kids can "pan" for crystals.