CA / Mountain Ranch, California
Calaveras County cave near Mountain Ranch with seasonal guided walking routes, one of California's oldest public cave histories, and reservation-only spelunking trips that go far beyond a standard show-cave walk.
- Best timing
- Late spring through fall, but check reopening status first because the official site still says closed for the season as of March 22, 2026
- Drive note
- Do not trust GPS for the final approach; follow the official San Andreas and Mountain Ranch directions and confirm the cave has reopened for the season before driving out.