Level 37 — commonly called the Poolrooms in Backrooms lore — is an endless run of tiled swimming pools and shallow water stretching away under a sourceless, sunlight-like glow. In the current canon it carries the name "Sublimity." Only the sound of water and its reverberations fill the silence, and no exit is ever visible.
Its dread comes not from ugliness but from beauty. The dissonance of a place as calm and clean as a resort yet entirely empty of people produces deep unease without any violence at all. It is the defining crystallization of the liminal-space aesthetic into a quiet horror that is "more frightening because it is beautiful."