In the Underdark region Badmaer is a cold sea that is more often frozen over than not. It is when it is frozen over that merchants and travelers switch from waterborne craft to ice vessels fitted with sails and skates. The ice usually breaks up during the summer months and then begins to freeze by Dreamer and is frozen to a depth of several feet to ten feet by the month of Kindle. In the western part of the sea is the port city Uromon. The drow city Phaerssysn has naval access to Throarstild, reachable by going up the river Finedhel.
The one area of Throarstild that never freezes over is the Damazandal river. This magical river cuts through the breadth of the area on its journey across many Underdark regions.