The actual temperature of the Cave of the Mounds is 50 degrees Fahrenheit, year-round. The cool cave air is protected from extremes of both summer and winter by thick layers of limestone rock.
“It’s the same principle builders apply to earth-sheltered homes,” said Anne Bandow, staff geologist. “That mass of stone would take a long time to heat up. It’s a very stable environment here – cool and moist and comfortable whatever the weather up above.”
While cooling off, visitors learn of nature’s underground marvels on the self-guided paced tours. High-domed chambers sparkling with crystals, mysterious winding passages and colorful mixes of minerals greet visitors at every turn.