Underdark

The Underdark is a vast, subterranean network of tunnels, caverns, and hidden worlds beneath the surface of the earth. It exists in various fantasy settings, like Dungeons & Dragons, and is often inhabited by diverse and often dangerous creatures, such as dark elves, mind flayers, and subterranean beasts. The environment is typically dark, cold, and maze-like, making it a treacherous place for outsiders. Despite its dangers, the Underdark is also rich in rare resources and ancient secrets, serving as a backdrop for adventure, exploration, and conflict.