Fog Doors, also known as Fog Walls, are found throughout the world of Dark Souls.
Fog Doors act as a barrier between certain areas and are often found before boss encounters. They are activated after choosing to "traverse the white light".
Before boss encounters it is impossible to use them in the opposite direction. One exception is the first encounter with Seath, in the Duke's Archives. They will disappear once the boss is vanquished.
Boss Fog Doors and area Fog Doors appear to have some slight differences between each other. Area Fog Doors appear as a darker shade of smokey white compared to Boss Fog Doors which look more like solid walls of light.
When being invaded, Fog Doors appear in the general vicinity to limit the staging area. Players cannot dispel invader-activated fog doors by walking through them or otherwise interacting with them and are deactivated when it is a failed invasion or the death of the player or the invader occurs.
- Northern Undead Asylum
- Undead Burg
- Undead Parish
- The Catacombs
- Darkroot Garden
- To the right of the locked door that requires the Crest of Artorias, separating the large area with many Stone Knights that eventually leads to the Moonlight Butterfly.
- Before the fight with the Moonlight Butterfly.
- The fog door appears in place of the large doors that lead to the area where Great Grey Wolf Sif is fought, but only after initiating the fight and if re-entering the arena before Sif is defeated.
- Quelaag's Domain
- Just before the fight with Chaos Witch Quelaag.
- The Catacombs
- Just after the second switch bridge.
- Before the Pinwheel boss fight.
- New Londo Ruins
- Directly opposite the corpse that carries the Parrying Dagger. It separates the initial indoor area and the "outdoor" catwalks.
- Appears after draining the ruins. It separates the large church-like building that houses a Mass of Souls and the large area that connects to the Valley of Drakes.
- Before the ruined tower that leads down to the Four Kings boss fight.
- Demon Ruins
- Before the encounter with Ceaseless Discharge.
- Traversing a fog door from the side not intended to be traversed from will give the player a message that says "Enter through the white light."
- If there is any enemy near the player while going through the fog door, an animation sequence will take place. This animation resembles a backstab however the enemy will also pull the player of the light before full transversment takes place.