I live on the banks of the Gonokawa River, the longest river in Western Japan, and yet it's less than 200K in length. Geologically speaking it's a very young river, not yet having had time to create an estuary. Like all Japanese rivers it is now dammed and a lot tamer than it used to be. The river was sometimes navigable all the way upstream into Hiroshima Prefecture, and that was the route the silver from Iwami Ginzan was shipped out. My village, Shimonohara, is about 18 K upstream from where the river enters the Japan Sea at Gotsu. These photos were taken from almost the same spot about 1K upstream of where I live. The top photo was taken in November.
This one was taken in May.
This one was June