Beneath the surface of Drovard are the vast, sprawling, cavernous environments of the Underdark. The Underdark is a network of subterrainean passages and landscapes with its’ own ecosystems and civilizations untouched by the light of day.
There are, generally speaking, three zones or layers of Underdark.
The near layer consists of largely regional areas of connected caverns and passages linking the surface world to the world below. They are a mostly dry wilderness. Not uninhabited, but lacking the diversity and populations of the “True Underdark”.
The middle layer, or true Underdark, is a vast and teeming realm of large subterrainean landscapes connected by all manner of passeges from networks of narrow tunnels to massive cavernous thuroghfairs that link an entire world below the world together. Rivers, lakes, and even underground seas provide for lush and exotic eccosystems, teeming fungal forests, and sprawling civilizations.
Below this are the bottomless pits and endlessly decending passages of the Deep Darkness where even the denezens of the Underdark fear to tred.