Mount Voormithadreth was a mountain in Hyperborea. It was a four-coned extinct volcano and the tallest peak in the Eiglophian mountains. During the age of Hyperborea, a variety of monsters and godlike beings lived in the system of caves beneath it, including Atlach-Nacha, Tsathoggua, Haon-Dor, Abhoth, and a culture of serpent people. The outer slopes of the mountain were inhabited by voormis, furry proto-humans.
It has been suggested that the name "Voormithadreth" is a pun, a lisped homonym for "voormis' address".
The gray-litten cavern of Y'quaa is the dwelling place of Abhoth, the Source of Uncleanliness. It is indirectly connected with the Cavern of Archetypes. Atlach-Nacha originated here. Y'quaa might be the true home of the enigmatic Ubbo-Sathla.
Cavern of Archetypes
The cavern of the Archetypes is a vast cavern inhabited by the spectral archetypes of all life on this earth. Nug and Yeb reside here.