The void is the endless empty space outside of the generated world, separated by two layers of bedrock.
The void below the world causes damage to the player in all. This is the only environmental way to die in creative mode.
The void in the overworld can be found below the bottom of the world, at Y coordinates less than 0. There are voids on either sides of the world (before Y at -1 and after Y at 1000), however these horizontal voids do not cause damage to the player.
The bedrock walls on either side of the overworld are not endlessly tall. The top of the wall is 300 blocks above zero. Scaling this wall is the only way to access the void in survival without exploits.
The nether has bedrock walls on each side of the world, making it virtually impossible to enter the void in this realm. The void behaves the same as in the overworld, only causing damage below the bottom of the world.
There are no bedrock barriers between the landscape and the void of The End dimension.
- At extremely high velocities, a player can phase through the bedrock layers (and, more rarely, other blocks) at the bottom of the world. This was made more difficult when timestep collision was introduced in 1.25.