Nether portal

The Portal is part of the October 31st Halloween Update. It consists of a frame of Obsidian, four blocks wide, by five blocks tall. The corners of the frame are not required, and only serve for aesthetic purposes. Once the frame is constructed, the player then sets the space inside the frame on fire, using a flint and steel, or Lava and a flammable block. This creates 6 portal blocks inside the frame, resembling a vortex.



When the player stands in a portal block for a few seconds, the player is taken to The Nether. The player can step out of a portal before it completes its animation to abort the teleport. A portal will also be created in the place where you enter The Nether, which you can again enter to be returned to the normal world. Building multiple portals on Earth within a certain proximity will all lead to the same portal in The Nether, and the same might happen vice versa.

In the event of two portals (Portal 1 and Portal 2) on Earth linking to the same portal (Portal A) in The Nether, it will be necessary to build a second portal (Portal B) in The Nether. To find Portal B's location, travel from Portal A in the same direction but only 1/8th as far as you would to get from Portal 1 to Portal 2 on Earth. The direction can be determined by either aligning yourself in the proper direction as you enter the portal, or by using certain texture patterns on blocks to orient yourself. To determine the proper distance, rough estimation will work most of the time. To be more precise, you can count blocks or time a run from Portal 1 to Portal 2 on Earth, dividing the time by 8, and then running that amount of time from Portal A.

The purple portal blocks emit light, so passive mobs may crowd around active portals at night. Like Bedrock, portal blocks cannot be broken (although they can disappear); however, they can be placed with modding. These portal blocks will automatically disappear after a few seconds, or when a block is placed adjacent to it. It only takes one block of portal to teleport to The Nether, though an inventory hack is needed to achieve this. The only exception is to place an obsidian block, and a portal piece next to that. The portal piece will disappear once the obsidian block is gone. Placing a portal block in a room then flooding that room will make the portal block disappear in SMP.

Portals can deactivate if there is fire adjacent to it (started by the player or Ghasts). TNT or an exploding Creeper can also disable a portal, but cannot destroy the surrounding Obsidian. It is possible to "re-ignite" portals by setting the space inside the frame on fire once again. If a portal is deactivated, and the player dies without activating it again, the next time they enter the nether a new portal will be created.

It has been confirmed that portals do not work in multiplayer yet; while they can be created, they can not teleport you. However, server settings can be changed in order to create a Nether-like world in multiplayer.

Pre-release, Notch suggested it would be possible for Ghasts to rarely appear on Earth near a portal. but Jeb later stated that the feature has not been implemented.

Also, it is possible to create a portal without possessing Diamond, by placing lava with buckets and converting the lava spawn blocks into obsidian with water. This can be done block by block within a mold, or by placing the lava spawn blocks under or directly next to water to create obsidian blocks in place. Any blocks within the portal need to be removed. This way you never have to destroy obsidian, which would require a diamond pick-axe.

If a portal, in either the nether or the normal world, spawns in midair, 4 extra obsidian blocks will be placed on both sides of the portal to prevent the player from falling.



Trivia

 * If you warp from world to world, the direction you are facing is maintained. (i.e. if you were facing east on the overworld and you warped to the Nether, you would still be facing east in the Nether)
 * An automatically generated portal may be built at a 90 degree angle to the one you entered. The direction you are facing is still maintained. (i.e. you may find yourself staring at the side of the portal)
 * If you place two portals on top of one another you will come out of the bottom one on the overworld and the top one in The Nether.
 * If you run out of Flint and Steel and disable all of your portals while in The Nether, it is still possible (although difficult) to reactivate a portal by having a Ghast's fireball hit the portal instead of you. Conversely, an active portal hit by a Ghast's fireball will be deactivated.
 * When you look through an activated portal with water behind it, the water will not be visible which will make squid easier to see.
 * Likewise, if you look through a portal with water in front of it, the portal blocks will be invisible.
 * Portal blocks are invisible if they are looked at from behind another portal block, mimicking glass.
 * Even when a portal is built with only 10 blocks of Obsidian (by leaving out the corners), the portal frame spawned on the other side will have the full 14 blocks.
 * It may be a glitch, but the player can strike portal blocks with tools, fists, and blocks, but objects will pass through them. This also explains why you can't put blocks and fire inside the portal frame while activated.
 * Riding a minecart into a portal has some adverse effects. The player can go through the portal, but remains stuck in the ceiling of The Nether. Reloading that saved world again will drop the player into the Nether, possibly without a matching Nether-portal and possibly right into a lava lake. Riding a pig or a boat through a portal also gives this same effect. The object you rode will stay on the Overworld side of the portal.
 * However, as of Beta 1.3_01, riding a boat or a minecart through a portal will cause the game to crash.
 * Zombie Pigmen grunts can be heard through portals.
 * If you are in your inventory and holding an item while travelling through a portal the text and the loading bar will be gray.
 * If TNT is struck before a player enters a portal, but does not explode, the TNT will explode upon the player's return to the Overworld. Likewise, furnace burning or redstone circuitry is suspended while in the Nether, and vice-versa.
 * Arrows get stuck on the portal instead of going through.
 * If you open a chest when waiting in a portal to leave the Nether, after spawning in the Overworld you can access the items in the chest until you close the inventory.
 * If a mob from the real world enters a portal, they will float in the portal as if it was water.
 * Portals can be constructed in SMP but they do not work yet. However, they will work in 1.6
 * If the game crashes while travelling through a portal, your inventory will be deleted and you will be re-spawned at your spawn point.
 * Mobs cannot use portals to teleport to the Nether, however they can walk through them.
 * Lightning can activate portals.
 * If you place a portal block obtained through Hacking beside another user-placed portal block, the first one will disappear.
 * You can still travel to the nether via a portal block placed on any tile using an inventory editor.
 * The self-destructive nature of a portal block makes it a useful tool for Multiplayer as a spacer as it makes placing blocks one off a surface significantly easier. This is most useful for taller fences which cannot be placed atop one another.  Another use of a portal block is to revert grass to dirt.  Hoe the grass to farmland, then place a portal block on top of it.  The farmland block will detect that the block above is not air and revert to dirt, and the portal will detect that the block below has changed and self destructs.

Media

 * On 29 October 2010 PC Gamer released this video, showing a portal being constructed and used.