Analysis of the sediment in Belize’s Great Blue Hole shows a concerning trend. Blue holes, the name for collapsed limestone ...

During periods of lower sea level, when caves were dry, stalagmites and stalactites ... geologic structure of the inland blue holes—deep, dark, sheltered, with little tidal flow—specialized ...

Visitors lowered themselves by rope into a dark, damp tunnel where the sounds ... maybe because of it), visitors flocked to ...

Dark Star’s passages are deep underground, yet many are 10,000 feet above sea level. The thin air at that altitude ups the physical challenge of negotiating the cave. Two days later I am at the ...

I slip under the ferns and into the cave — it feels a little like being in a Hawaii lava tube — and venture to the back, which is far but not too far. It’s damp and dark inside, and the ...

Kartchner Caverns State Park, Alabaster Caverns State Park, and Onondaga Cave State Park are some of the caves travelers can ...