Wall or river? The internet is freaking out over this confusing pic

Remember the Dress? The Dress? Of course you do, and by the way, it was black and blue.

That was able to be put to bed pretty quickly because all it took was someone to take an actual, non-flash photo of the dress and the world was righted back to it's original axis. However, the brain-twisting conundrums of visual trickery have returned, and the internet is preparing to spark a civil war with itself over this photo. So tell us, what do you see here: A wall? Or a river? Or you could just be the most laid-back person of all time, like this dude: