The Drygully Tunnel was an entrance to the Underdark at the edge of the High Forest, less than two-days' marches away from the small village Trollbridge. While the humans in the area did not know much about the tunnel, the drow used it regularly for raiding attacks upon the inhabitants of the World Above. The human berserker Fyodor used it to escape the Underdark after he learned from Liriel Baenre of its existence.