Do you mean dark, as in spooky. Yes I agree though I didn't really see it. I think #1 sets that mood. And you know it is there in real life too. I grew up on a farm which had a waterfall. The rocks were black and the water also. There was a scariness about that water. Though in its dark depths were only turtles and eels. But maybe it captures a little bit of our fear of nature. There are dangerous things there. In these forests, the mostly like worst thing is the Giant Stinging Tree. But in this river, people have drowned as they've been sucked under the water and lost in the rocks below. So what you perceive is entirely accurate. Thanks for bringing it to my attention.