Different things being discussed here - hardest, most dangerous, and scariest are all different. But, I would vote Russell Fork or CC of the Tuolumne for all three.
Gore, Clear Creek...I'd rather swim either of these than the Russell Fork or even certain drops on Sec. IV. People used to think the Gauley was soooo dangerous because of the prolific undercuts, but the fact is, if you stay in the main flow of almost every rapid there, you're gonna be fine. I think you have to look at the margin for general error, the margin for recovery from those errors and the consequences for bad mistakes, and Gore and Black Rock are serious water, but they just don't hand out death like a bad move or swim in a rapid like Fist or Crack-in-the-Rock.
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