Population: Unknown (aboleth, cloaker, drow, duergar, illithid, quaggoth, svirfneblin)
Government: City-states, each with different government (autocracy, magocracy, matriarchy, monarchy, theocracy) and so on)
Religion: Varies, usually racial pantheon
Imports: Armor, food, slaves, timber, weapons
Exports: Armor, exotic goods, magic, weapons
Alignment: N, LE, CE
The region called the Underdark is an entire world beneath the feet of the surface dwellers of Faerûn. Inhabited by monstrous and evil creatures that shun the daylight, the Underdark teems with entire cities and nations of derro, drow, duergar, and mind flayers (illithids). It is also home to even stranger races such as aboleths, beholders, and kuo-toas, as well as slaves of just about any intelligent humanoid found on the surface.
These evil beings battle or trade with each other for resources, magic, and power, forming alliances that collapse when plots unravel or better opportunities come along. Interspersed with the warring city-states are enclaves of gnomes, svirfneblin, dwarves, and other neutral and good folk, who remain isolated or resist encroachment by malign neighbors.
Life and Society
The Underdark is a harsh realm where two overwhelming drives rule: survival and the destruction of your enemies. Perpetually dark in most regions, the Underdark is filled with creatures that long ago developed darkvision or enhanced senses to compensate, often becoming intolerant of true light as a result of their adaptation. Some places are dimly lit by glowing rocks, luminous crystals, or phosphorescent moss, lichen, and fungi. Bizarre plants are common, and visitors usually find it impossible to identify which are hostile or poisonous without magic or potentially lethal experimentation. The most precious resource is fresh water, since the Underdark has no rain and inhabitants must rely on whatever filters down from the surface. Those who discover water hoard it and protect it with their lives.
Because of the scarcity of certain resources, each city often specializes in producing a few items and trading these with neighbors in peaceful times. A typical trade caravan consists of several dozen heavily armed merchants and soldiers, with two to three patrols sent forward or behind while traveling. Although the tunnels are generally silent, echoes travel far, and a skilled Underdark scout learns to recognize subtle signs of natural animals and lurking threats by their echoes alone. Wealthier cities teleport caravans to their destinations or use existing portals to speed travel, and access to a convenient portal is often the cause of lengthy wars between nearby cities. Cities that develop a reputation for killing or enslaving caravans in peacetime (as opposed to exhibiting cool hostility and rudeness, which are expected) usually find themselves cut off from valuable resources and made easy prey for aggressors.
Major Geographic Features
Because most of the Underdark has been only cursorily surveyed, and given that the largest caves are only a few miles long, few geographical features would be considered noteworthy to a surface dweller. Lakes tend to be the largest features, although the nearby stone may dip below the surface of the water, breaking it into quasi-separate regions that can only be identified as the same body of water by the most meticulous cartographer.
Tunnels in the Underdark extend for miles, some ballooning into caverns thousands of feet across, only to shrink to narrow spaces too small for a halfling to squeeze through. The largest cavern halls become representations of the surface in miniature, with hills, valleys, underground rivers, and lakes. In this three-dimensional environment, most races make use of the walls and ceilings of their caverns, accessing the higher levels with natural or magical flight or levitation or wall-crawling mounts such as giant spiders or certain breeds of lizards.
The Underdark is divided into three general levels. The upper Underdark is close to the. surface, has considerable interaction (trade, raids, or conquest) with surface races, and is mainly inhabited by drow, beholders, dwarves, mind flayers, svirfneblin, and - under cities -wererats. Water and food are relatively abundant, and adaptation to darkness is mild.
The inhabitants of the middle Underdark tend to see surface races as slaves. These include drow, lone aboleths, cloakers, derro, mind flayers, svirfneblin, and kuo-toas. Water and food are difficult to find.
The lower Underdark is incredibly strange, filled with alien societies and bizarre cultures, hostile to any unlike them, ruled by aboleths, cloakers, derro, and mind flayers. Food and water are very rare, so the races here prey upon each other for survival. Adaptation to darkness is often extreme, with new and peculiar senses appearing in some monsters. All levels contain evil humanoids, usually as slaves in civilized cities.
Araumycos: This great fungus fills the Underdark beneath the High Forest between one and three miles below the surface. Possibly the oldest living organism in Faerûn, the fungus predates the empires of the elves. It cannot reach beyond the borders of the forest above it, and pieces of it taken away quickly die, so it may be magically or symbiotically tied to the forest. While susceptible to fire, acid, and similar attacks, it is immune to magic. No effort has eradicated much of it for long, and it sometimes unleashes psionic attacks upon its attackers. Occasionally entire portions die, revealing ruined cities or colonies of fungus folk, but the cause and origin of the growth remains unknown.
Giant's Chalice: This brackish lake in the lower Underdark curves from the northwest of Proskur, under Inaebor, and around to Elversult. Inhabited by intelligent octopi, the Chalice is thought to have connections to the Sea of Fallen Stars. Vampiric squid introduced into the Giant's Chalice by the illithids now threaten the octopi. A glowing coral that lives only in this lake is a great prize and one of the few luxury items the octopi export.
The Labyrinth: This maze of unclaimed passageways fills the upper and middle Underdaik in the region between Red Larch and Triboar on the Long Road north of Waterdeep. Used by northern Underdark merchants heading for Skullport and beyond, the Labyrinth is known to have shifting walls and dangerous inhabitants - particularly baphitaurs, sorcerous beings thought to be descended from minotaurs and demons.
While great realms tend to expand to the limits of a particular cavern system, endless tunnels link the Underdark together.
Blingdenstone (currently abandoned): Founded in the Year of Fragile Beginnings (-690 DR) by svirfneblin fleeing the phaerimms, Blingdenstone became a self-sufficient city-state that only rarely made contact with other nearby civilizations. Jolted out of their isolation by Menzoberranzan's attack on Mithral Hall, the twelve thousand deep gnomes allied with the defenders of the dwarfhold and helped stem the drow onslaught.
The defeated drow had their revenge several years later: Dozens of bebiliths were summoned into Blingdenstone by gate and planar ally spells, slaughtering most of the svirfneblin. The five hundred or so survivors fled with their belongings to Silverymoon, where their small community was welcomed into the Silver Marches. The Silveraen hope to resettle and fortify the city as a defense against further drow incursions.
Cairnheim (Village, 500): Founded by stone giants fleeing a slaughter of giantkind by the dwarves of Shanatar, Cairnheim (located under the Giant's Run Mountains in the Dragon Coast) has been ruled for the last fifteen hundred years by the Dodkong, an undead stone giant chieftain. The undead monarch has corrupted the giants, and he reanimates each clan chieftain who dies forming the Dodforer, a council of "Death Chiefs" that serves him.
Cairnheim giants use runecasting, preferring necromantic spells acquired from Velsharoon. The Dodkong is known to be a sorcerer of considerable power. At the rare times they engage in trade, the giants exchange gold, silver, and nuggets of adamantine for rothé, rare fungi, and wine. The giants of Cairnheim have darkvision and carefully watch over their access tunnels, which are protected by runes, avalanches, and deadfalls.
Deep Shanatar: The first and greatest shield dwarven realm, Deep Shanatar controlled the upper Underdark where Amn, Tethyr, and Calimshan are now. Originally spread across eight subkingdoms that battled in what are known as the Spawn Wars, the dwarves of Shenatar eventually convened to form a lasting peace, ruling from the Wyrmskall Throne, a seat of authority that could be moved from kingdom to kingdom.
Over time, the declining birthrate of the dwarves and their emigrations north caused the empire to fall apart. Wars with other Underdark races claimed the subkingdoms, leaving only Iltkazar in the modern day. Ruins from Deep Shanatar can still be found scattered over its old territory. While most ruins were looted, remote outposts turn up from time to time (often as monster lairs with masterwork dwarven armor, weapons, and even magic items within them.
Gracklstugh (Metropolis, 34,900): Also known as the City of Blades, this duergar nation rests in the middle Underdark just south of the Evermoors. Consisting of a large grotto of hollowed-out stalagmites that borders on an Underdark sea called the Darklake, the gray dwarves use the stone pillars as smelting centers, building their homes and workshops around them. The duergar control territory for several miles around their home city, allowing only visitors intent on trade. A large standing army enforces their claim. The city is also home to derro, thousands of slaves, and a small number of stone giants from the Cairngorn clan. The city exports fish, mining equipment, and quality steel arms and armor. The derro are the true rulers, controlling King Tarngardt Steelshadow VII (LE male duergar Ftr17) and the clan leaders with bribes, magic, and threats.
Iltkazar (Small City 7,500): Surrounded by hostile neighbors, the shield dwarves of Iltkazar control little more than the city itself and its immediate surroundings under the Omlarandin Mountains in Tethyr. Iltkazar is one of the eight original dwarven kingdoms of Deep Shanatar.
Unlike other Underdark nations, Iltkazar has many tunnels to the surface, most connecting to old and carefully guarded dwarven ruins. A river and its tributary run through the city, providing fresh water and driving winches, pumps, and other mechanical devices. The city's ceiling is covered in faintly glowing silvery blue lichen. Other fungal growths are cultivated for food and as fodder for a small herd of rothé. Three-fourths of the inhabitants are shield dwarves, a little over one-tenth are humans, and the rest are rock gnomes or svirfneblin. Slavery is illegal in Iltkazar, and runecasters, warriors, and clerics guard the mithral doors that allow access to their city. The city specializes in engineering, the working of rare metals, and gemcutting.
Menzoberranzan (Metropolis, 32,000): North of the Evermoors and under the River Surbrin, Menzoberranzan is a matriarchal drow city famed as the birthplace of Drizzt Do'Urden and the launching point for the attack on Mithral Hall. The city's population is one-third drow, the rest being humanoid slaves. The city trades poisons, tasty mushrooms, riding lizards, spell scrolls, wine, and water.
The city is defended by drow troops (both full-time soldiers and armed members of the noble houses) and slave forces, with spell-casters aiding defensive efforts. Although Menzoberranzan is ruled by a council of matrons from the eight greatest houses, others in the city hold political power, such as the mercenary leader Jarlaxle (NE male drow Ftrl7) and the Archmage of Menzoberranzan, Gromph Baenre (CE male drow Wiz20).
Although the drow are generally cool toward visitors, a few small businesses cater to adventurers and traders. Over one hundred tunnels link the outskirts of Menzoberranzan's territory to other parts of the Underdark, the most notable being those near Mithral Hall in the heart of the Moonwood, and on the western edge of the High Forest. The city has recovered from its losses during the Time of Troubles and the attack on Mithral Hall, and it again plans expansion and the conquest of its neighbors and the surface realm.
Oryndoll (Metropolis, 26,000; 3,450 mind flayers): This city of illithids is in the lower Underdark, beneath the center of the Shining Plains. Hoarders of knowledge and jealous of information, the illithids are rarely visited by any but slave traders. Although it long ago fought a great war with the dwarves of Shanatar, Oryndoll is best known in the Underdark as the birthplace of the modern duergar race, bred from the dwarves of clan Duergar in the hopes of creating a loyal race of skilled dwarves with mental powers. These gray dwarves led a series of uprisings and escaped from the city, causing so much chaos that the city was saved from collapsing only by a manifestation of the illithid deity Ilsensine. The mind flayers of the city have since developed a highly religious culture and innovations in psionics. The city teems with mind-controlled slaves and an uncounted number of cranium rats.
Sschindykyn (Large City, 15,000): This drow city is on the shore of Lake Thalmiir, miles beneath the King's Forest of Cormyr. The drow of Sschindylryn are skilled in divinatory and travel magic, particularly spells and items that locate food, water, and minerals, and they trade these things with other cities through a network of portals in their city and in the shallow part of the lake.
The Sschindykyn drow used to be more warlike, using their portals to make surprise raids on other cities. A major defeat by Menzoberranzan curbed this practice, and they now stick to trading while they rebuild their strength. The city is built on a kuo-toan ruin, both above and below the water, and even the new architecture retains a piscine style. In addition to the magic trade, the drow fish the lake and farm local algae that thrive on faerzress.
Sshamath (Metropolis, 45,009): Rare among subterranean drow cities, Sshamath is ruled by male wizards, with the female clerics of Lolth taking lesser roles. This community under the Far Hills is the preeminent Underdark market for magic items. Considered as a strong trading partner by other cities, Sshamath is well protected by warrior-wizards.
The drow males gained ascendancy through successive generations of predominantly male births, decreasing the number of drow matrons and their power over the city. Its permanent and artistic faerie fire-like lights on the walls are unusual for an Underdark realm but make it convenient for surface visitors who lack darkvision. Slaves make up a fourth of the population, and visitors from other realms, undead servants, and conjured creatures bring the usual head count to sixty thousand. Anyone with skill at wizardry or sorcery is welcome to visit the city without fear of enslavement.
The history of the Underdark predates and parallels that of the surface world. Progenitor races arose in the Underdark and died out over time or were slain when their equivalents retreated underground in the face of Opposition from new races such as elves and dwarves. Ancient races such as the kuo-toas disappeared from the surface before recorded human or elven history. Evidence of the illithids' origin is scarce, but sages believe that the mind flayers arose at nearly the same time as the kuo-toas or invaded from another plane during that empire's height. The aboleths are also ancient, but the history of their machinations from the lower Underdark has gone unrecorded.
The drow entered the Underdark after the Crown Wars, roughly -10000 DR, with evidence of the first drow cities built around -9600 DR. A vigorous and aggressive race compared to those extant, they seized a great deal of territory before falling into endless internal wars. Dwarves, always present on and below the surface, battled the drow and other Underdark rates, losing the entirety of clan Duergar to the mind flayers only to see them emerge generations later as the duergar subrace, imprinted with the cruelty of their psionic masters. The derro also emerged during this time, bred from captured dwarves and humans by the illithids. In later millennia, races such as the svirfneblin, goblinoids, orcs, and grimlocks. were brought or found their way into the Underdark. The most recent arrivals are the cloakers, which have been present only for the last few centuries.
War, conquest, decay, and collapse form the familiar cycle of the Underdark nations. Cities fight each other for riches, resources, or slaves, or out of age-old hatred. Stable empires grow decadent or suffer from numerous and constant skirmishes that bleed away their power. Failing empires collapse, sometimes from within and some times prompted by the blades of their enemies. From these broken cities come groups of survivors who find niches where they can scratch opt an existence and eventually build new cities.
Plots and Rumors
For surface adventurers, simply entering the Underdark and returning to tell the tale is an accomplishment of note.
Dead Reckoning: A band of skeletal dwarves in full battle regalia is making its way through the tunnels, slaughtering any who attack them except for dwarves. Their dead foes shed flesh and rise as skeletons to join the march. These undead are unaffected by the turning and commanding powers of clerics, and they detour to avoid dwarven settlements. Their goal may be the reclamation of an old dwarven burial site from enemy hands or the destruction of a powerful foe, such as a deep dragon.
Hit and Run: Given the number of portals and undiscovered tunnels in the Underdark, it is possible for a raiding or trading party of drow, duergar, kuo-toas, or any other such race to appear in any surface area, seeking mayhem, slaves, or profit. If such a group didn't have an easy way home, it might wait out the daylight in a cave, rum, or abandoned warehouse, or under the protection of a local wizard or evil temple.
Sidebar: Travel in the Underdark.