Off the beaten path in San Antonio, Texas, the Natural Bridge Caverns are definitely worth going out of your way. Go deep into the Earth for a subterranean tour through vast chambers, deep passages and thousands of beautiful formations that have been slowly building (an inch a year!) for centuries. Guided Discovery Tours lasting 75 minutes give you insight into the formations, and for those truly adventuresome, join the Discovery Adventure Tour or the Hidden Passages Adventure Tour. Yes, you’re going to get dirty on these spelunking adventures!

Guests 10 and older can join the three-hour Discovery Adventure Tour, which includes climbing a 25-foot, mud-covered slope and belly-crawling through the “Birth Canal” tunnel. For kids 13 and older (and their dirt-loving parents), try the four-hour Hidden Passages tour where you’ll be lowered by rope into deep caverns.

For more information, visit Natural Bridge Caverns.