(Lowerdark of Chionthar)
Beneath the vale of the Chionthar River, between the Northdark and the northern marches of Old Shanatar, lies a tremendous abyss known as Throrgar. This yawning chasm is about 50 miles across, although mighty buttresses rise up out of its fathomless darkness at odd intervals to meet its ceiling. Several foolhardy individuals have descended into Throrgar, and those who have returned report that the small portion of its bottom they explored lies about 15 miles below its ceiling.
Throrgar is a place of fierce, never ending winds so powerful that strong human warriors standing near its edge have been plucked off and hurled screaming into the horrible gloom of the chasm. The air rushing past wind-scoured stone results in terrible high-pitched piping, deep groans, and nerve-shattering wails that seem almost purposeful. The wind in Throrgar is never below strong in intensity, and it often reaches hurricane force.
The depths of Throrgar are riddled with planar connections to Cocytus, the second layer of Pandemonium. In the heart of the abyss, great castles that house slaadi, demons, and strange elder things are carved into the mountain-sized columns.