The Underdark refers to the lands that lie below the surface of the earth. The Underdark is a strange alien landscape populated by bizarre creatures and ancient races, nearly all of whom are hostile to surface-dwelling life. One of the key connections is as a source of silk from spiders, and other rare foodstuffs found only there. This is in direct competition with the silk road that runs from the Oriental lands to the Western World.
The Underdark is a many-layered network of caverns, passages, and rivers of water and magma. Its stone ceilings look down on strange features: stalagmites sharp as dragons teeth, lacy rock curtains, arches, and graceful bridges. A heavy, brooding silence is broken by far-borne echoes. They magnify sounds of life, cracks and deep boomings of shifting shattering rockfalls and the murmur of moving water.
The Underdark is extremely dangerous, especially to those not native to it. There are the usual dangers associated with caverns: claustrophobia, occasional poor air circulation, and getting lost. There is no light except for occasional patches of fluorescent fungus; most Underdark inhabitants either have highly developed senses other than sight or have developed infravision or ultravision. Food can be extremely difficult to find and much of the natural vegetation is poisonous. Some think the Underdark is permeated with a magical energy. The Drow call this faerzress, which is used as a source of energy by the native plant life but which interferes with scrying and teleportation spells. These forces are strong, and the rock gives off radiation akin to magical energy. Drow have learned to use and thrive among these energies. These radiations prevent teleportation magic from operating reliably in the Underdark. The maximum range of such travel is half a mile. A teleport will travel straight for half a mile, then divert into the nearest open area - even if it is a tiny cavity enclosed in solid rock! Near very strong radiation, teleports are reduced to blink range, or have involuntary displacement effects.
In addition to those dangers, the Underdark is also home to many predators and a wide array of races, most of which are hostile to other races as well as their own kind. These races include:
Known Underdark cities and locations:
Known entrances to travel to the Underdark from the lands above: