In 1992, when I was researching the cave sequence of Dinotopia: The World Beneath, I traveled to the central mountains of Puerto Rico, where you can find some extensive limestone caverns that are safe to explore as long as it hasn’t been raining recently.
Near the Camuy caves, I hired a local guide to take me alone into a private cave system just outside the publicly open sections. We rappelled down into the sinkhole and headed about a mile underground, swimming across underground lakes and moving carefully along the rims of weird limestone bowls.
Giant albino spiders clung to the walls, and there were forests of pale sprouted trees that grew from seeds carried in by bats. The guide pointed to a scorpion. “Touch him, you will die,” he said.
After a few hours of passing through a long series of chambers, we arrived to a point where waterfalls blocked the route and we could go no farther. At that point there were carvings of Taino deities, apparently used in some pre-Columbian initiation ceremonies.
I was really nervous, especially when I extinguished my light by ducking my helmet underwater while I was swimming—but I tried to keep my knees from shaking. As we returned, my guide calmly told me about how, at the very spot where I was wading through muddy water, he happened to step on the dead body of a man who was the object of a search and rescue.
All these experiences were grist for the imagination. One of my inspirations for this sort of research is science fiction writer Alan Dean Foster, who is far more intrepid and well-traveled than me, and who bases all his science fiction novels on his treks.
Check out this BBC video about the ultimate crystal cave in Mexico
Via Best of YouTube