California Caverns, Natural cave system in Mountain Ranch, California, US

California Caverns is a cave system in Mountain Ranch containing multiple chambers filled with stalactites, stalagmites, and flowstone deposits. The passages wind through different levels connected by approximately 60 steps distributed across five staircases.

The cave system was discovered by miners during the Gold Rush, originally called Mammoth Cave, and became California's first show cave open to the public. This early opening as a tourist attraction established it among the state's pioneering natural destinations for visitors.

Visitors can still see more than 5,000 historic signatures carved into the cave walls, a practice begun in the 1850s when guests were handed a candle and a nail at the entrance. John Muir wrote about his visit in his 1894 book The Mountains of California, and Bret Harte and Mark Twain were also early visitors.

The two main tours guide visitors through illuminated passages with secure walking paths across the different levels. Sturdy footwear is recommended since the passages are uneven and narrow in some spots.

Visitors can still see more than 5,000 historic signatures carved into the cave walls, left by early tourists who were handed a candle and a nail at the entrance. Local folklore holds that Captain Joseph Taylor found the entrance by accident while setting up target practice.