Hueco Mundo is located between the living world and Soul Society. It can only be accessed by ripping a hole in the dimensional fabric separating the worlds. Unlike Soul Society, where travel requires specialized gates, hollows can travel to and from Hueco Mundo at will.
The landscape of Hueco Mundo is a seemingly never-ending white desert, with dunes like those of the Sahara. The desert is littered with what appear to be boulders and shriveled trees, but these are actually a form of quartz. In Hueco Mundo, the Moon is on the opposite lunar phase of that in the human world. Like Soul Society, the atmosphere is filled with spiritual energy, but it is more concentrated, thus allowing hollows to gain nourishment despite the lack of human souls.
Like that in real world deserts, active life in Hueco Mundo appears to be few and far between. Hollows generally seem to dwell below the surface or in other areas until something provokes them to leave their shelter, like the intrusion of a foreign entity. According to the shinigami, all hollows dwell in Hueco Mundo regardless of their shape, size, or power. In the anime, hollows can also drag other spirits into Hueco Mundo, as seen with Orihime Inoue's brother, Sora. In this case, Sora was forcefully made into a hollow by several others and sent against Ichigo Kurosaki.
