Hueco Mundo (虚圏 (ウェコムンド), Wekomundo; Spanish for "Hollow World", Japanese for "Hollow Sphere") is the dimension in which Hollow and Arrancar usually reside. It lies in between the Human World and Soul Society.
An unchanging night covers the sky, an endless white desert covers the ground. The tree-like objects are not plants, but rather quartz-like minerals.The landscape of Hueco Mundo is a seemingly never-ending white desert, with a multitude of dunes, littered with boulders. In Hueco Mundo, the moon is on the opposite lunar phase of that in the Human World. The vast desert seems to lack any bodies of water and contains rocky formations. Like in Soul Society, the atmosphere is filled with a high concentration of Reishi, thus allowing smaller Hollows to gain nourishment despite the lack of Human souls.