Hmm, I think I'll take that as a challenge. I'll have to look it up.
I didn't think I was all that scared of dark, confined spaces until I went spelunking with my dad once (my idea, too). It's not because it's dark that you easily get lost; it's because you have to think in three dimensions, and it's surprisingly easy to forget which way is up. And all of a sudden you realise the place you were trying to get to is too small to crawl through, and you turn to go back and you can't remember whether you took the passage up, left, right, or down. For a moment I thought we'd gotten lost in what seemed like a fairly small cave, and I was so relieved to finally see the light coming from the entrance.