Are there secret dimensions in minecraft?

Solution 1:

Firstly: Herobrine never has existed in the game. His only real existence was added as a joke by Notch with the reference in the update notes

• Removed Herobrine

Therefore the reference to a "Herobrine Dimension" is also false.

Secondly, a "Sky Dimension" is only a mod that was made to be the opposite of the Nether, which was very popular in the earlier days of Minecraft, and led many to believe it was part of the original game.

This also led to many other mods creating similar mods to alternate "dimensions", like the Twilight Forest, but that's all they are: mods.

So to answer plainly; the only "alternate dimensions" that can be found within the Vanilla Minecraft game are the Nether, and the End.