At Nevada Falls in Yosemite, there is a spot just above the falls that is almost flat with lots of ledges for people to sun themselves and dip their feet into the water. But, if you wind up in the current it is a very quick trip over the falls, height of about 600 feet. When we were last there, there wasn't even a warning sign, let alone a barrier. I believe there have been incidents at that location. Makes for a great (if last) selfie...