Sky dimension

The Sky Dimension (otherwise known as the Skylands, Floating Island Dimension, Dream World, or Heaven) is a work in progress by Notch. It "performs well, [but] looks ugly". The Sky Dimension was originally planned for the Beta 1.8 Adventure Update but soon shown that it was a work in progress.

In a live webcast on the Swedish gaming site feber.se Notch revealed that the Sky Dimension would "probably be a dream world" and that when "you go to bed there is a certain chance that you get dragged into the dream world instead. Then you will be able to do it on purpose later on.."

Due to the obviously vast differences in terrain and appearance, The Ender is quite unlikely to be the same as the Sky Dimension as was first thought.

History
The Sky Dimension was first announced by Notch tweeting a picture of the dimension. It was probably made to be like a "heaven," because the nether was considered to be and act like a hell. The sky dimension was not completely confirmed until Notch released an update via Twitter stating: "And because PC Gamer made such a big deal of the sky dimension, I guess I'll have to finish it. Consider it confirmed."

The Mod-Enabled Version
Notch left data in for an early prototype of the sky dimension in Beta 1.6 and 1.7. Using various mods it is possible to access this currently unfinished version of the Sky Dimension.

In this version of the sky dimension it is always midday and it does not rain or snow (though cloud cover does appear as if it were raining). Although uncommon, it is possible to find Sugar cane, Redstone, Lapis Lazuli, and more rarely Diamond. Like the normal world, you can also find Dungeons, Iron, Coal, and Gold. The only mobs that currently spawn in the sky dimension are chickens and very rarely cows and pigs. Below the islands of the sky dimension is nothing but the Void and a layer of clouds.

Bugs
On an extremely rare occurrence, Sky Dimension biomes may generate in the overworld. This is most likely due to world corruption like the Nether may generate in world corruption. The biome upon the Sky Dimension in the overworld is Plains. This is more common in multiplayer.

Trivia

 * If you select a map while in the unfinished version of the Sky Dimension, your game will display the saving chunks screen and crash, because the current implementation of maps can’t handle exposed sections of the void.
 * Maps work in the Sky Dimension in SMP.
 * The Sky Dimension is an inversion of The Nether, whereas the latter is a huge rock filled with air, the former is a huge sky filled with rock.
 * The Sky Dimension, similar to the Nether, has weather disabled. This may be because of the fact that it is above the clouds.
 * In Indev there was a World Type called "Floating" It spawned floating islands full of terrain based on the World Theme.

Videos

 * Notch's Sky Dimension in Minecraft Beta 1.6.4
 * Notch's Sky Dimension in Minecraft Beta 1.6.4 - Exploring with Hot Air Balloons!