The Sub-Tunnels are a series of sub-worlds in FNaF World. They are commonly known as "Glitch Worlds", and the player must navigate them to travel to parts of the Overworld. Fredbear warns the player not to goes down four tunnels because if they do, they cannot get out of the 4th tunnel.
The player will enter the first tunnel after running into a Glitched Object. White and blue lines can be seen moving across the screen. The trees in this sub-tunnel are white with a blue outline. Freddy will turn into a white 8-bit version of himself with a blue outline. To return to the overworld, the player must run into a pulsing "Orange Blob".
When a player runs into a Glitched Object in the first sub-tunnel, they will enter the second tunnel. Wavy lines will distort the screen. The trees are rounded cubes and their trunks are sticks on the bottom of the cubes. Freddy becomes a Freddy head with a top hat. To return to the first tunnel, the player must run into a cube that shrinks, returns to its normal size, then shrinks again.
In this Sub-Tunnel, the background is white and the objects are black. Trees are rectangles on sticks and Freddy is a block with a face. Black lines will be seen moving on screen. To return to the second Sub-Tunnel, the player must run into a cube that rapidly shrinks, returns to its original size, then decreases again.
If the player finds the secret passage to another glitched object, they will enter the fourth Sub-Tunnel. The background is black and objects are red. Freddy turns into a red 8-bit version of himself. The player can not get out if they enter, once in, they can either talk to Old Man Consequences or run into the lake.
If the player talks to Old Man Consequences, he will tell them they gone to deep into the code and they can not get out. He asks the player to fish with him, and the end will appear.
If the player falls into the lake, Freddy will appear to be falling in a never-ending pit. About two minutes later, a person can be seen with their arms around two smaller people looking at a flashing light. The screen will stay like that until the game is closed via task manager or by F2.
- In the teasers, they were called the "World Between World".
- The player can walk in all 8 directions in the sub-tunnels.
- Walking in 8 directions was intended in the overworld, but it was unused.