Hueco Mundo

Hueco Mundo is located between the human world and Soul Society, though it is separated from the bordering dimension known as the dangai. It can only be accessed by tearing the dimensional fabric separating the worlds, which allows hollows to travel to any other dimension at will. Depending on the hollow, the effect for this varies. Regular hollows usually appear from a small black vortex or form out of smoke, while menos-class hollows quite literally tear the sky apart to emerge. Arrancar use a more stable variant of the latter technique known as garganta.

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 the anime, the seemingly small trees are shown to extend far underground, and support the desert above. Hueco Mundo exists in perpetual night, and 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, 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. With the exception of the arrancar, most hollows dwell below the surface or in other areas until something provokes them to leave their shelter, like the intrusion of a foreign entity. This is expanded upon in the anime: underneath the desert of Hueco Mundo is a vast cavern called the Menos Forest, where most hollows take refuge. According to the shinigami, all hollows dwell in Hueco Mundo regardless of their shape, size, or power.

In the anime, hollows have also been shown to be able to 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.