We have a lot of slot canyons in Arizona and Utah. But none of them is filled with a huge, cold waterfall. This river in Canada disappears into this narrow slot to reappear a few yards downstream. I have see some local slot canyons that are about the same length. Of course the lush vegetation goes with the Canadian climate and location, but we have a lot of water some of the time with flash floods or we wouldn't have slot canyons at all.