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. The cavern borders on the Dreamlands Underworld, and Atlach-Nacha originated here. Y'quaa might also 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.