Most people don't understand the extreme danger of a waterfall or dam. When water falls over the edge, it entrains air. At the bottom, the water is white from all the air bubbles it contains. This water is significantly less dense than normal water, and even the best swimmer CANNOT swim to the breathable air above. Even Olympic swimmers will drown in the water below a waterfall or dam.
I’ve swum in the plunge pool of a couple of healthy waterfalls without any issue from water turbulence or air bubble density.
The biggest worry for me was a large stick or log floating over the top and falling.
And this is corroborated. Thank you.