The Nether

The Nether is a dangerous, volcanic, fungal dimension resembling a hellish underworld. It contains fire that never goes out; vast oceans of lava; Nether fungi and normal mushrooms in place of plants; many unique mobs, mostly hostile in nature; and exclusive structures, resources, and biomes.

To access the Nether, the player must construct a Nether portal in the Overworld (portals created in the End do not activate). To create the portal, the player must first build a rectangular obsidian frame, ranging in size from a minimum of 4 blocks × 5 blocks to a maximum of 23 blocks × 23 blocks. Once the frame is completed, it can then be activated by placing fire within the frame, using flint and steel, fire charge, dispensers, or any material that is capable of igniting fire.

The portal allows most entities (with the exception of the wither and the ender dragon) to be transported to a corresponding portal in the Nether. In Survival, the player must stand in a Nether portal for 4 seconds to enter the Nether. The player can step out of a portal before it completes its animation to abort the teleport. The portal plays a sound effect while the player is inside it. If there is no corresponding portal, a new 4×5 portal is created. The portal can be destroyed by breaking the obsidian frame, by a nearby explosion, or by placing water in the Overworld or lava into it with a bucket or dispenser. Any of the blocks in the corners can be destroyed without destroying the portal.