I ran across this story a few days ago. Its a very well written account of what happened when two cavers decided to explore a tiny hole in a cave. Then expanded and expaned the whole until one person could squeeze through. And then, weird stuff begins to happen....
The debate is wheather on not the story is true. Either way, its a very good story. Its super long, but very entertaining.
http://www.holyshiite.com/caver/page1.html
Enjoy..