I grew up in Iowa, near the Mississippi River. As kids we would swim in the big muddy to cool off from the heat and humidity. If you stuck your arm in the water up to your elbow, you couldn't see your fingertips.
This made the rope swing particularly exciting because just as you pushed off someone would inevitably yell "Hey isn't that a log floating out there?"
"Yikes! Whoooaaaahhhhhhhh! Wherrrrrrre?"
I remember dreams as a child. How wonderful it would be to swim, and fish for trout, and float in cool, clear water.