Crack in the Rock
For me it's Crack in the Rock on section IV of the Chattooga. It's not a a difficult rapid but I get the heebies each time I'm above it and coming through Corkscrew. The first time I had paddled that stretch, after an overnight drive from Wisconsin, a member of the sheriff's office was there and informed us that someone had died in Crack the day before. He asked us to keep an eye out for a body and if we saw something to call the office. Needless to say it was a pretty somber day on the river for us.