寧靜之水（Quiet Water） 是Undertale 的原聲帶專輯里面 第33首歌。It is primarily based on the Ruins theme. This track plays in parts of Waterfall that are more populated, be that near Gerson or the Nice Cream 傢伙. It also plays in Hotland at Muffet's Spider Bake Sale. Compared to the speed in the game files, it plays slower in-game and in the OST.
Like most of the music tracks within Undertale, this song is also profusely slowed down during the Genocide Route.