Niagara

One of the 15+ foot waves in the Himalayas section of Whirlpool Rapids.
Niagara river rapids above the falls.

If you ever ran the falls you might as well run it in a barrel. At that hight it does not matter what you are in, kayak, tube, raft, ducky... (that would be interesting to watch). You are going to get torn out of your boat on or before impact and if you are lucky they might find your body.
Jesse had guts but that is just suicidal.

Video of First Legal Descent of the Niagara Gorge

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What river is this?
Looks like a nice surfing hole...

Just got back from a touristy visit of the falls, and had to look at the gorge of course. From under the bridge you have about a half mile long rapid. A few guard holes on the top right, but you pretty much want to be in the middle. From there, no more holes. Just huge water. Lots of massive V waves, that cycle, build and explode from time to time. A lot of the run is going to be about luck and timing. All the rest is just hitting your roll and not even thinking about taking a swim. There is a slight lull between the first rapid and whirlpool. From the scout whirlpool would be best taken left to right. You definatley DO NOT want to be on the left at the bottom or you will get slurped by one of the most evil whirlpool boil thangs you have ever laid eyes on. Around the corner from whirlpool is one more wave train and then some smaller rapid. According to the park, the gradient is 54 feet per mile and the run is 1.6 kilometers.

As a side note, the rapids above the falls would be a hoot, but missing the last eddy would re-define 'SUCKS'.

If you are ever stupid enough to run the falls, the mad dash from the canadian side would be the way to go. You can get a car with in 100 feet of the water, and only have to hop a 4 foot tall fence. From there, peal out and you'll have about 75 feet of fast moving flatwater before the bottom drops out.

I'm the first kayaker to survive running Niagara Falls! Haha, just kidding, I cropped it!