The Story
In 1900 prospectors Frank and Albert Michaud felt cold air blowing from a hole, enlarged it, and found a cavern lined with sparkling calcite crystals — Jewel Cave. Theodore Roosevelt proclaimed it a national monument on February 7, 1908, the first ever established specifically to protect a cave. By 1959 less than 2 miles were mapped; then cavers Herb and Jan Conn pushed it past 64 miles by 1979. As of mid-2025, over 220 miles are mapped, making it the second-longest cave in the U.S. — and experts think that's under 5% of its true extent.
Surprising Facts
→ It was the first national monument in the world established specifically to protect a cave (1908).
→ In 1959 under 2 miles were known; today over 220 miles are mapped.
→ Scientists estimate only 3-5% of the cave has actually been explored.