One day when I was a kid, an epic thunderstorm rolled in. My friend and I went straight for the small creek nearby. We were expecting it to be flooded enough to be worth swimming in but when we got down to it it didn't seem like it was up more then a few inches.
For a short section the creek went through a bit of a field, instead of being a few inches deep and a few feet wide it was about foot wide and maybe a foot deep but kinda muddy on the bottom.
So my 5 foot tall friend stepped into what appeared to be about a foot of water and promptly vanished. He couldn't swim worth a shit, so I had to locate him and drag his ass out of there.
Being the idiots we were, we did it a couple more times until the water went back down.
You know that feeling when you think you're at the bottom of the stairs but actually have one step left? Imagine that, except into fast moving muddy water that's over your head.