Spoiler Alert: This article or section contains details about plotlines not covered in the anime. Do not proceed unless you wish to be spoiled.
A «Teleport Gate» (転移門,Ten'i-mon?) is a feature that allows fast travel between the floors of Aincrad. It is located at the central plaza of the main settlement on each floor. The Teleport Gate allows free teleportation to any other floor where a gate is activated. This happens after the player(s) who beat the boss of the previous floor's Labyrinth opens it.
In the world of Aincrad, Teleport Gates are the primary means of travel, as physically travelling from floor to floor via Labyrinth mazes is dangerous and time-consuming. The Teleport Gates are also present in New Aincrad and the Teleport Gate in New Aincrad's Town of Beginnings also connects to a gate in Yggdrasil City, allowing players to travel between the World Tree and New Aincrad.
A Teleport Gate can be used by either standing in the middle of an active Teleport Gate or by using a Teleport Crystal, when teleporting from an area outside of a Teleport Gate, and by saying «Teleport (転移,Ten'i?)» along with the name of the destination city.
Once a floor boss is defeated, the victorious party can activate the gate of the next floor by merely entering the main settlement and touching the surface of the portal.
This causes a blue light to spread everywhere, marking the floor accessible via teleportation to any other existing floor in Aincrad. The event is known as a «Town Opening».
In the event that the victorious party does not manage to activate the gate after reaching the floor, the Teleport Gate will automatically activate after a two hour period.
The gate can only be activated for use if the name of the destination village is known, however, the players are able to check their map for the name of the village. They are also able to learn the name of the village or town from other players allowing lower level players to access higher floors.