Underdark

Tavern tales across Faerûn’s sunlit lands whisper of the Underdark, a lightless, subterranean realm that is home to fabled races and ancient, unspeakable evil. It is a domain of primeval mysteries and unending war, a hidden world of cruel masters and hopeless slaves, filled with monstrous races that were old before humans were born. It is a dank, dismal place of fungus, rot, and slime. It is a land where a few lucky merchants have found a lucrative trade, but where many more have been slain (or worse) for their effrontery. So dire is the reputation of the Underdark and its denizens that mothers caution their children to behave, lest the dark elves steal them away.

A proper account of the Underdark must include the cold

machinations of the hateful illithids, the unwholesome cities of

the drow elves who pay homage to the bitter Spider Queen, and the

unending servitude of the lesser creatures that fall into the

clutches of these two races. Unlike the upper world, where civilization

and the light of day protect travelers from horrors, the

Underdark holds the promise of deadly peril. Illithids, drow, phaerimms,

and aboleths vie for supremacy in its dark tunnels and sunless

seas. They fight one another with armies of slaves, terrible and

ancient magic, and mind-shattering psionics for control of the

encompassing tunnel systems and the extended caverns, vaults,

cavities, gaps, and nodes that riddle the earth beneath Faerûn. The

Underdark is literally an entire world, most of which is inhabited

by monstrous and evil creatures that shun the daylight. Hundreds

of independent cities, towns, and strongholds are scattered

throughout the caves and caverns that make up this realm.

Tunnels in the Underdark extend for miles, some ballooning

into caverns thousands of feet across, only to shrink to spaces too

narrow for a halfling to squeeze through. The largest cavern

halls are often representations of the surface in miniature, with

hills, valleys, underground rivers, and lakes. Most races native to

this realm make use of the walls and ceilings of their caverns,

accessing the higher levels via natural or magical flight or levitation,

or even wall-crawling mounts such as giant spiders and

certain breeds of lizards.

The Underdark is divided into three levels. The upper Underdark

(Upperdark) is close to the surface, and its residents have

considerable interaction with surface races. The inhabitants of

the middle Underdark (Middledark) tend to see surface races as

potential slaves. The lower Underdark (Lowerdark) is an incredibly

strange place filled with alien societies and bizarre cultures

hostile to those unlike them.

An Underdark Primer

While many surface dwellers regard the Underdark as all the

same (one big cave, infested with hungry monsters), the wise

adventurer prepares by studying what surface dwellers know

about the Realms Below before venturing underground. Knowing

what sorts of creatures and dangers lurk at what depths

might mean the difference between life and death.

The Underdark is divided into three general levels: The

Exploring the Underdark

What squelches through unlighted corridors

miles below the daylit surface

world? What secrets of ancient vintage

rest behind long-cooled barriers of solidified magma? What perils

and terrors await those foolhardy enough to venture into such a

dismal and dangerous environment? Adventurers from all over

Faerûn dare the depths of the Underdark in search of fame, fortune,

and power, but all too often they find only death—or fates

even worse than death.

Geology and Environments

A cave is a natural opening in rock that is large enough for creatures

to enter. The Underdark, simply put, consists of a linked

network of several titanic cave systems. Large portions of it do

fit the definition of “a natural opening in rock,” but the Underdark

also encompasses areas of deep water that hide coral caves,

hollowed-out sections of ice in which creatures live, and places

where fungus, bone, or even pure force form “caves.”

Underdark terrain is dynamic and changeable. A map drawn

a few decades ago may show tunnels that have long since collapsed,

or lakes that are now dry. Terrain can change gradually

over the course of decades, centuries, and millennia, or swiftly as

a result of an earthquake or volcanic eruption.

The Underdark Environment

Walking through wild caves without end is different than stalking

monsters in a dungeon near the surface. Travelers venturing

into the Underdark enter a world in which nothing can be taken

for granted. Vast portions of the Realms Below are wastelands

devoid of food, water, and even light.

Spelunking

When traveling in cramped natural tunnels and through

narrow, low corridors that vary widely in diameter, it is difficult

to move as quickly or fight as efficiently as normal.

Underdark Encounter Tables

The Underdark is a vast region encompassing more square miles

than can easily be calculated, especially considering the three-dimensional

nature of it. Outside “settled” caverns and vaults,

the dark rootways below the mountains and plains of Faerûn

constitute a wilderness.

Geography

Faerûn’s Underdark includes drow cavern-cities, sunken

wondrous vistas shrouded in everlasting darkness. This

chapter describes some of the most notorious, important, and

incredible locales in the Realms Below.

The locales described here do not represent an exhaustive

list of the Underdark realms. Uncounted hundreds—perhaps

even thousands—of deeply buried caverns and lightless cities

exist beneath Faerûn, and virtually every surface-world dungeon

seems to connect to murky depths from which all sorts of

horrors can spew forth. Consider the places discussed in this

chapter to be the ones that knowledgeable surface folk know

of, and a sampling of the types of places that deep-delving

heroes might explore.

Underdark Domains

Faerûn’s Underdark is not a single, continuous cavern system,

and even places on the same level may not connect to each

other. The existence of Underdark settlements beneath Waterdeep

and Raven’s Bluff, for example, does not mean that it is

possible to travel from one city to the other underground. In

fact, the Underdark consists of a number of discrete domains. A

domain is simply a collection of Underdark locales among which

underground travel is reasonably easy. In certain places it may

be possible to trailblaze a route from one domain to another, but

then again, it may not.

An Underdark domain is something like a large island in the

surface world. It may feature several distinct terrains and cultures,

but it’s possible to travel all over the island without having

to set sail on the ocean. Similarly, two locales in a single domain

are connected by enough cave systems, tunnels, and other passages

to enable travel from one to the other without leaving the

Underdark. Cities and settlements in the same domain are much

more likely to engage in diplomacy, trade, or warfare than cities

in separate domains. Like the continents or regions of the surface

world, domains tend to group disparate cultures together

and force them to interact with each other for good or ill.

Faerûn’s Underdark consists of seven major domains, a dozen

or so minor ones, and hundreds of otherwise isolated locales that

don’t appear to connect (at least not easily) to any other Underdark

networks. The major domains include the following.

Sites of Interest

The following entries describe cities, ruins, dungeons, and other

points of interest that adventurers might wish to visit in the

Underdark. A history is given for each, and for some of the

more complex areas, descriptions of important sites and NPCs

are included.

Each of the following entries includes a parenthetical note about

its depth (Upperdark, Middledark, or Lowerdark) and its domain

(or geographical region, if it does not belong to a major domain).

Unlike surface cities, Underdark cities tend to be monocultural.

In many places, anyone who isn’t of the dominant race is

either a visitor or a slave. To reflect this arrangement, any city

with a sizeable contingent of slaves has a separate notation for

the slave population in its community statistics block. The population

and racial breakdown of the free residents is given first,

and then the slave population. Community assets are calculated

from the total population because slaves do help to generate

wealth, even if they don’t hold any of it.

Dungeons in the Underdark

A “dungeon” is traditionally located underground, and no part of

the Underdark fails to qualify for the term in that respect. For

the purpose of adventuring in the Underdark, a dungeon is any

locale or extended area that offers the possibility of adventure,

danger, and treasure. By this definition, the Underdark contains

literally hundreds of dungeons. A few of the most infamous or

dangerous are described below.

Magic of the Underdark

The Underdark eclipses nearly all surface-world locations

in terms of the sheer power of its magic and

its alien and frightening psionics. Who doesn’t fear

the deity-channeled malice and might of Lolth’s clerics? Worse

yet are the mind flayers, whose psionic and magical superiority

over most other races is as terrifying as their sinister appetites.

Less well known, and therefore more mysterious, are the aboleths

of the Lowerdark, which harbor secrets of ancient lore

within their alien, unfathomable minds.

Beyond what is generally known or rumored, the Underdark

shelters a wealth of strange power and magic. The long-hidden

past. The gloamings and the slyths have abilities that few intelligent

creatures (even other Underdark races) understand. And

finally, there is the whispered rumor of node magic—a secret

lore that allows those with the proper training to channel power

from the earth itself.

Lore of the Underdark

Myriad are the paths to power, as the old archmages like to say,

and the Underdark is home to at least as many variant types

of magic as the surface world. Circle magic, rune magic, and

Below. Cooperative circle magic is favored by the grimlocks of

spellcasters may accomplish things together that even the most

powerful of their fellows could not dream of achieving alone.

city of Dunspeirrin. And the Shadow Weave—the pattern

formed by the negative space between the Weave’s strands—is a

secretive, shadowy magic that has gained many converts in the

Underdark, including the kuo-toa of LoobliShar.

than they are on the surface. The primary practitioners of such

powers are the duergar, the illithids, and the aboleths.

The Underdark also offers one other variant kind of magic

that is, for obvious reasons, available only below the earth. This

form of power is called node magic.