I've not seen the documentaries you refer. But kayakers know that danger of a water feature doesn't necessarily correlate with how violent it looks on the surfa

I've not seen the documentaries you refer. But kayakers know that danger of a water feature doesn't necessarily correlate with how violent it looks on the surface. Plenty of very quiet weirs are known to be fatal while plenty of noisy ones (though not all!) will spit you out unharmed.