Sinnbjorg is a twisting river that is always changing course. It flows through the glaciers of Igas and between them where ice and snow has not moved to cover it. In other areas near Anubeth it is reduced to steam or constantly being shifted from the changing landscape of the two elemental regions it flows through.
Sinnbjorg is formed from the meeting of the lava and glacial flows coming out of Igas to the east and Anubeth to the west. The river can be steaming hot in some areas or frozen over in others but where it between these two extremes, it is a hazard clogged with icebergs and strewn with the bodies of those fighting in the Thrones War. The river ends at the fog-shrouded bay Jargauti.