Dvořák's Rusalka

One of my favorite soprano aria, Song to the moon, comes from Czech opera, Rusalka!

Rusalka is a water nymph who wants to have human soul from the Prince's kiss.

If she transforms to a human shape, her voice will be muted. This is exactly the Disney's Mermaid story, however every characters die at the end of the opera. This is such unpleasant and depressed.