The Grey Marshes are located in eastern Velnitia, where the land gradually drops down to meet the sea. The far eastern parts are salt marshes, with many places where there's no clear delineation between land and sea.

There are three major landmarks in the Grey Marshes, called the Three Sisters, which gives the region its name. Three active shield volcanoes that spew ash and smoke. The ash has spread to cover much of the land, giving it its grey colour.