Interesting that you can get 0.6 mi. of distance out of it. It must be of decent size and maybe even unusual for a largish river w/o much water motion? How deep, how clear?
I guess swimhole is the wrong term. It is the Lamprey River and I could swim miles in it. But to get into the water it is like sliding down a hole - looks like a beaver slide.
The river is about 50m wide and is 1 - 3 meters deep. Water is dark-ish. It clears after rains but can collect tree debris after longer warm spells. Two days ago, the light was right to see blue dragonflies diving down to the water surface catching small bugs. And always 1 - 3 FDFs chase me after a while.