Belgium La Hoëgne

This spot along the river forces all the water of the river trough here

Tripod needed low light conditions most of the time

Along the river is a hiking path with several bridges that cross the river. You can park at two places and go back and forth along the river, and see different viewpoints. The hike is 3.6km along the river between the two parking spots.
The parking spot I've added is the smaller one, but you don't have the go through the river with you car. And you follow the river downwards, you just have to hike back when you have your shots and it's easier with that adrenaline rush :)