I glance at my guide, Brian Kakuk—one of the world's foremost cave divers. He appears unfazed ... structure of the inland blue holes—deep, dark, sheltered, with little tidal flow—specialized ...

The limestone slope of Potholes Cave ... dripping stalactites and plastered by popcorn-like calcite formations. Descending deeper, the cave transformed into tall, narrow, clean-walled rifts, full ...

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 ...

Take a deep breath and dive below the surface with cave-diving experts and scientists in the video above. Find out what it takes to plunge into the dark and mysterious world of underwater caves. Caves ...