This is the Bolton Strid. Many call it “the most dangerous river in the world”. And they’re not wrong: if you were fall in the specific bit of the river shown in the picture, your chances of dying are around 95%.
The Strid is part of the River Wharfe in Yorkshire. As you can see from the picture below, the river is fairly broad a few miles north of the Strid.
So here’s the thing: as it narrows to a space an adult could easily jump over, all that water has to go somewhere. In this case, it goes down, and over the centuries the current has dug trenches as deep as 40 feet (12m) in some places. This means the river effectively turns sideways through the Strid.
But here’s the killer: the first 4 feet (1.2m) of water in the Strid move at a leisurely pace: around 5mph (8KM/h) on a normal day. So ducks can take-off, land and float down the river without a problem. But underneath that there’s another layer running between 25-30mph (40-48KM/h). It’ll sweep you off your feet in an instant, and if you get pushed into one of those 40 foot deep trenches… you’re not coming out. Ever. Not alive, anyway. No amount of human muscle-power can outswim that current, and even if a fully-equipped rescue team watched you fall in, there’s just NOTHING they could do to rescue you.