The Nether



The Nether, also referred to as "the Nexus" in Notch's blog and previously known as Hell and the Slip, is a hell-like dimension accessible only by entering a Nether Portal from the Overworld.

The Nether can be used for traveling large distances on the Overworld quickly, as 1 block in the Nether equates to 8 blocks in the overworld. The Nether is home to exclusive mobs, items and blocks, some of which can only be found in the Nether.

The Nether functions as a second map in a player's world. When it is entered, the chunks from the Overworld map are unloaded and the Nether chunks begin to load. Terrain generates infinitely in the Nether just like in the Overworld. If the player dies in the Nether, they will respawn in the Overworld; but the contents of their inventory will remain in the Nether, assuming that the items do not land in either fire or lava, thus burning up.

Terrain


Its terrain is largely composed of Netherrack, which is arranged into large, smooth outcroppings and niches; it is essentially a cave. There are patches of gravel and soul sand, as well as stalactites of glowstone hanging from the ceiling. Mushrooms grow abundantly in the Nether, and natural fires are a common sight. Small tunnels form in the netherrack, which contain Nether Quartz, but no hidden caverns. Nether fortresses can be found as well. These Nether fortresses are made up of Nether brick, Nether brick stairs, Nether brick fences and crops of Nether wart. At the very bottom, beneath an ocean of lava, is a layer of Netherrack and bedrock. The very top of the Nether is also bedrock.

Navigating the Nether can be very dangerous. The strange, dimly lit landscape conceals pits and sudden cliffs. Many lava streams flow from the ceilings, down the Netherrack and into a lava ocean. If one dies near this lava or a patch of fire, it is a safe assumption that some of one's items will fall in and be burned. There is hidden lava which you might find if you dig randomly, and lava flows more quickly in the nether in the 1.5 update.

The sky and fog in the Nether are dull dark red. Thunderstorms can cause the shade to flicker quickly.

In the Xbox 360 edition, world sizes are limited to 862x862 blocks. In the Overworld, the edge of a map generates an ocean and (mostly) smooth shores, whereas in the Nether this limit is formed by a wall of bedrock that abruptly cuts off the terrain. These bedrock walls aren't smooth at all, as they seem to be generated in the same way as the bedrock located at the bottom layers of a map.

Accessing the void on top of the Nether
The max world height is now 256 instead of 128 blocks. This allows for mobs to spawn, mushrooms to grow, and blocks to be placed above the bedrock surface.

There are several ways to access this void:


 * 1) Stand just below the bedrock, using pistons to shove the player into the Netherrack, then disconnect from the game and reconnect. On reconnect, the player will be spawned in the next free space above, which is above the bedrock.
 * 2) Place one boat on a block with one block of air between it and the ceiling, which needs to be one block thick, and place another boat on the one thick ceiling. Get in the boat, and hold right click to access the void. Sit in the boat on top and reconnect to go back down.
 * 3) Throw ender pearls at the bedrock, throwing fast enough to get through. The ender pearls apply a slight y boost and repeating this can be used to go up through a block, but does not work sideways or downwards. The "Limbo" area above the Nether is an extremely efficient place to travel since there are no pigmen to block rails, or netherrack to block Ender Pearl teleportation.
 * 4) Dropping gravel on the player. Typically portals created in the Nether spawn an Overworld portal at about the same height as the Nether portal.
 * 5) The easiest method is of course to switch to Creative mode. It is then possible to break the bedrock like any other block. This, however, does not work on SMP servers (for obvious reasons) unless you're an op.

Environment
The Nether has no day/night cycle and no weather. The only natural sources of light are fire, lava, portals, and glowstone. A dim ambient light can be seen throughout the Nether, but this is purely a visual effect and does not affect game mechanics; this dim light is actually what light level 0 looks like in the Nether. Just as in the overworld, there are 16 levels of brightness in the Nether, the brightness granted by a light source is reduced by one level with every transparent block it radiates through, and each light source casts the same level of light it would cast in the Overworld.

The Nether does have one special property relating to light: in the Nether, plants that usually require a minimum light level, such as flowers and Nether wart, can survive in complete darkness--or what passes for "complete darkness" in the Nether. However, due to a bug, this doesn't work below natural veins of glowstone or below lava source blocks that appear naturally in cave walls. Plants at any level below these formations, even if separated by other terrain, will uproot if not adequately lit.

Blocks and structures
Entries marked with a D require additional data to fully define the block. Entries marked with a T have tile entities associated with them to store additional data. Items with IDs in red cannot be legitimately obtained in the player's inventory in the game; they can only be obtained by the use of inventory editors or in multiplayer using the /give server command. Items available only in Creative mode are in blue.

Naturally generated
Naturally Generated includes blocks that are created through the world seed.

Naturally created
Naturally Created means a combination of events that cause a new block to be placed by natural causes, not the player.

Structures
These blocks are generated as part of Nether fortresses. Even if the "Generate Structures" option is turned off, Nether fortresses are still created.

Nether-affected materials
There is no way to place water in the Nether in a Survival game. Using water buckets will produce steam and an empty bucket. Ice can be picked up using Silk Touch, but will not produce water when broken or melted in the Nether.

Trees grow normally, and their leaves take a dead-looking brownish color like in desert biomes. Care should be taken when planting trees, since the abundance of fire and lava can ignite them very easily.

It is always a good idea to bring an empty map down into the Nether and activate it there, as getting lost is easy and can happen frequently. Note that maps do not work as expected in the Nether. Since maps plot down from the top of the region, the scenery will be covered by the Nether's ceiling. The player's direction will be spinning randomly and not provide any use. Nonetheless, maps can still be used to see where the player is in a specific area and can help them backtrack the way they came. For maps to display the Nether, they must be activated there.

Compasses and clocks can be brought in freely or crafted in the Nether, but they will not work correctly. As the Nether is in a totally different dimension from the Overworld, compasses will be unable to find the original spawn point, and clocks will not determine the position of the sun or the moon. Their arrows and dials will instead spin and flail madly. Beds will explode when a player attempts to sleep in one. This can be a useful strategy to quickly mine materials in the Nether, but only if the difficulty is set to peaceful.

Lava flows twice as far in the Nether as it does in the Overworld (generally 8 blocks, instead of 4 blocks). Building Snow Golems will only cause them to melt due to the Nether having a very high temperature.

Mobs
The Nether is home to its own share of mobs. Nether mobs are completely fire-proof and can often be seen wandering into lava, where it will take them a while to get out due to the slowdown it causes on movement.


 * , huge jellyfish-like creatures, will lazily hover around. They are 4×4×4 blocks large, and have 9 tentacles hanging from them. If they spot the player, they will shoot fireballs at them, which can be deflected by shooting arrows at them, punching them or hitting them with any tool. The reflected fireballs will instantly kill the Ghast, if it is hit. These will explode and often leave craters, if the blast-site is weak enough. They make screeching and whimpering noises, something like a purring kitten or an angry baby (actually taken from C418's cat), and can be heard from great distances. Also, they can be killed by firing 2 arrows and hitting the Ghast. If killed, they drop gunpowder and/or a ghast tear, which is used in potions.


 * spawn in groups and wander aimlessly. They will not harm the player unless attacked. If they are, all the Pigmen within a 32 block radius rush the player, often causing ambushes from behind as the player attempts to attack while fleeing. If killed, they drop rotten flesh and sometimes a gold nugget, and even more rarely a golden sword that sometimes has one or two low enchantments, such as Knockback I or even Sharpness II. Other golden objects may also drop, like a helmet.


 * are found in Nether fortresses and are primarily spawned through monster spawners found inside the fortresses. They are able to float and shoot 3 fireballs at the player in a quick succession. They appear to catch fire just before shooting fireballs, then "cool down" until they can shoot again. If killed, they drop Blaze rods.


 * are spring-like mobs that look and behave similar to Slimes that slowly hop towards the player. If killed, they split into 2-3 smaller versions of the original one. Magma Cubes are moderately rare. If killed, they drop magma cream, which is used in Brewing.


 * are the Nether equivalent of Skeletons and spawn in Nether fortresses. Unlike skeletons, however, Wither Skeletons use stone swords and are over two blocks tall. When hit by a Wither Skeleton, the player may be inflicted with the "Wither" effect for a few seconds, darkening the health bar and further damaging the player. When killed, the mob may drop coal and bones, and very rarely drop their skull and the stone sword. The skulls are the key items to creating the Wither boss.


 * rarely spawn in Nether Fortresses.

Overworld mobs like pigs and zombies do not randomly spawn in the Nether, but they can wander or be shoved through a portal. Throwing chicken eggs and constructing golems works as normal (however, Snow Golems will die from the heat). Creative mode spawn eggs work normally in the Nether.

Portals


Nether portals are made by creating a 4x5 (2x3 on inside) door frame out of obsidian and then lighting the inside of the frame on fire with flint and steel or a fire charge (fire charges can be launched at the portal frame with dispensers to activate it, preferably right next to it, allowing automatic ignition). When the player stands inside the portal for the first time, it will create a portal in its equivalent area of The Nether. A loading screen will appear during the change of worlds. See the Nether Portal page for more information on portal mechanics.

File save location
The Nether is saved in the same way normal worlds are, but instead of mixing the world files inside the save folder, the files for Nether are stored in %appdata%/.minecraft/saves/Worldname/DIM-1 (on Windows), whereas normal world files in %appdata%/.minecraft/saves/Worldname. Note that DIM-1 does not contain its own level.dat, as the same level.dat in the upper folder is used for both Overworld and Nether. This means that even if a player changes the level data in the /world folder for a particular save, Nether portals will still take the player to the Nether world originally generated for that save and vice versa.

The Nether Reactor
For the moment, there is no kind of Nether in Pocket Edition. There is however, a structure known as the Nether Reactor. It is built from 14 blocks of Cobblestone, 4 blocks of gold and 1 Nether Reactor Core. It can be seen here: http://www.twitch.tv/jbernhardsson/b/337680976. The alternate Nether is very different from the regular dimension available in the Computer and Xbox 360 Edition. First The alternate Nether is just a Netherrack room, and items randomly drop. There are Zombie Pigmen, although the hat layer on their texture is missing and they appear to be hostile.

Trivia

 * The idea for the Nether came from a transportation method used in the novel series The Wheel of Time by Robert Jordan. Within this transportation system, the Ways, people could travel a massive amount of distance in a few days instead of weeks. Like the Nether, the Ways has many dangers. Notch also once said that Jake, his co-worker, was a big key to the Nether. It isn't clear exactly what that means.
 * The ceiling of the main Nether Cave reaches a maximum y value of 109 at eye-level. (111 when standing on the ceiling) This makes levels 115-125 great for making minecart rails connecting different destinations in the Nether that are free from Ghasts. However, in 1.5, there will occasionally be lava there.
 * When the player warps from worlds, the direction the player is facing is maintained (e.g., if the player is facing east in the Overworld when the players warp to the Nether, the player will still be facing east).
 * While inside the Nether, furnaces will stop smelting and plants will stop growing/decaying in the Overworld. However, the day/night cycle continues and all the Mobs present are maintained. This is due to chunks loading and unloading.
 * One of the Level themes in Indev was Hell. It was a normal map, but with a lava ocean, perpetually dim lighting, and a black sky with dull red clouds.
 * If the player stands on soul sand with lava at the same level adjacent to the soul sand, the player will take damage if he/she steps near the edges of the soul sand. This is due to soul sand being slightly smaller than other blocks.
 * There may be some areas where the ocean/lake of lava may go under an overhang and the lava will not illuminate that area. Going in there and creating light (placing a torch, lighting a fire, etc.) will fix this.
 * Pressing in the Nether will display the biome as "Hell".
 * When leaving the Nether and entering the Overworld, any nighttime mobs that were present the last time a player was within update radius of the portal will still be present, even if it is now daytime. Undead will begin burning as usual, but spiders which were already targeting players will continue to do so.
 * Mushrooms can spawn on top of the top layer of bedrock in the Nether.
 * After using a Nether portal, you will be wielding the first item on your hotbar.
 * In the Xbox 360 Edition:
 * There is a wall of bedrock surrounding the map to stop the player from crossing the map limit as shown here.
 * Wolves cannot enter the Nether.
 * Music from the Overworld will stop and will play a new theme in the Nether only heard from this edition. When exiting, the music will revert back to the Overworld's themes.