I think one of the things that made helped make Splash Mountain so good is it actually did this!
Recall the Fishing Place leading into the first choir of Laughing Place: It was very subtly done, but the lighting became progressively darker the closer you got to the second drop, before finally you reach it and you would notice there's no more happy music, just a dark pit, a kinda creepy laugh from Brer Rabbit, and the somewhat unsettling (or little me thought so) yells of pain from Brer Fox, before drop!
As I said, it was subtle, but it did an incredible job of building tension and creating a feeling of unease without you even realizing it.