Isn’t this just a modern version of going over Niagra falls in a barrel?
There’s a much greater volume of water, and a lot of turbulence at the base of Niagara Falls. I have visited Palouse Falls, and photographed it, several times. I don’t know how deep the plunge pool is, but I doubt there are any boulders in it. Not that I would undertake such a stunt, being basically a non-swimmer, but for a daredevil so inclined, this seems a suitable site for it.