Void

The Void is the empty space under each map. It can be seen through gaps in the lowest layer of Bedrock. These gaps only exist on regions of a map that were generated prior to the Halloween Update.

This space is blue in color, and will change from light to dark depending on the time of day. During the day, it will also give off light like a torch. Falling into the Void will cause the player's health to rapidly decrease by 2 hearts, killing them in at most five hits, or about 2.5 seconds. After respawning, the player will have lost all held items with no way to recover them, as they have fallen out of the map.

A red Void can be seen above The Nether if one uses a map editor to make a hole in the top bedrock layer. Unlike the normal Void, you will not take damage when you are standing on top of the Nether.

Items, falling Sand and Gravel, and mobs will disappear if they fall into the Void. Water and Lava will appear to flow into it, but will not actually spread and form beneath the lowest layer. This effectively prevents players from descending into the Void safely via swimming. Blocks cannot be built on the underside of the Bedrock layer.

There is currently a bug in SMP that will remove chunks client-side, so while the data is still there, the client cannot see it and will glitch if they step on it. This can be fixed by reconnecting, placing a torch next to the missing chunk or changing the fog distance by pressing F.