That sounds like the place I swam in as a kid. We called it Mule Hole. The area with the 10-12 foot rock overhang was the main swim hole but upstream of this were a series of waterfalls that the river over the centuries had bored chutes and tubes in one could ride down and shoot out below the falls. I was in grade school and slim and trim then. But if you can get in same the size stays the same throughout. The main down side was the stone tunnels and slides could wear out denim shorts, pockets and all, in a few hours, regular bathing suits would last a fraction of that. If you did not bring some other pants going home would not have many stops. Mule Hole also had a mountain spring in the wall on the other, Eastern I think, side. I would hope it is still drinkable, but it was ice cold when it came out of that wall and ran done to the river. You do have to be able to swim back with a pitcher of water in your hand to enjoy it with meals. Now the current seemed calm in that deep hole that is about 20 feet deep, but I know one time I had started from the last falls base, and was going downstream to where a friend was on a rock and his face suddenly had a panic look as he pointed in my direction, when I began to drift back upstream I went to a freestyle stroke and beet the whirlpool pulling me toward it. So from time to time the current gets visible. Now a half mile or so up stream was a wide shallow area with sink holes. I think that was a river crossing point over a century back. I stepped into one of the sink spots and found a large wagon wheel rim, and rolled it back to the swim hole to show others. Well it was too big to bring home, at least six feet in diameter, and got left there. As I understand it was used by others to contain a camp fire on the rock and when they left for home, they pushed the fire and wagon wheel rim into the hole. It may be about 20 feet down in the swim hole, somewhere downstream, or somebody rolled it back to a vehicle and took it home for a pot rack or something. Before you go to get it you might want to remember it will be light in the water, but gets real heavy once it's above water. And take some extra cloths.