A great mysterious force of nature of Vendrith. Often considered the edges of the plane of Materia. Colloquially just called the fog.
Manifests more in some places than others. The fog exists in its main and most dangerous form out at the “edges of the world,” such as out at sea, which once made the Discovery of Horiza impossible. Reaching the Horiza is still an arduous journey because of the difficulties of safely navigating the fog passage.
The fog may take other forms which ebb and flow more however, and may even exist farther inland and “approach from above, not beyond.” The regions of Ferweth (Fog of Ferweth) and Vilhun are both known for struggling with the fog.