Minecraft wiki entry for The_Nether, associated text: The portal allows most entities (with the exception of the wither, the ender dragon, and entities riding or being ridden by another entity) to be transported to a corresponding portal in the Nether. In Survival, the player must stand in a nether portal for 4 seconds to get to the Nether. The player can step out of a portal before it completes its animation to abort the teleport. The portal generates 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.