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.
LIGHT
Except for any lanterns that characters bring into the caves, the Underdark is absolutely dark. Coupled with the tomblike silence of most passages, absolute darkness can unnerve even the most experienced caver. Thus, extra lights and oil (or magical means of illumination) are important for any cave trip.
ARTIFICIAL ILLUMINATION
Halflings, humans, and other surface dwellers without darkvision must absolutely carry some form of light with them in order to navigate the Underdark. While torches or lanterns are feasible for relatively short trips, a journey of more than a few days might require dozens of torches and oil flasks, making nonmagical light impractical for long expeditions.
The best and most efficient means of providing light in the Underdark is to use minor alchemical or magical items, such as sunrods or continual flame torches. A sunrod is small, light, and long lasting, capable of providing illumination in a 30-foot radius for 6 hours. A party of explorers could easily carry several dozen sunrods, which would provide enough light for many days of travel. At 2 gp apiece, an investment of 100 gp or so is well worth the money.
The continual flame torch is potentially cheaper, since the material component costs only 50 gp and the item lasts forever if not destroyed. However, such a torch only illuminates a 20-foot radius.
NATURAL ILLUMINATION
While most of the Underdark is exactly that, some locales possess sources of natural illumination.
Luminescent Growths: Rare forms of lichen, fungi, and moss are bioluminescent. In sufficient quantities, these growths can illuminate large caverns. Most bioluminescent growths are quite dim, so a cavern illuminated by glowing moss or fungi is typically as dark as starlight, although some particularly bright regions might be equal to moonlight.
Molten Rock: Areas with exposed pools or streams of magma are illuminated by the dim, ruddy glow of the molten rock. The glare of molten rock is typically equal to moonlight.
Radiant Crystal: Some rare rocks of the Underdark are naturally radiant, ranging in brightness from starlight to full daylight, although daylight equivalence is quite rare. The great vault of Deep Imaskar is roofed with radiant crystal that is as bright as weak surface daylight.
Reflective Stone: While not naturally luminescent, caverns made partially of reflective stone can be much more easily illuminated by small light sources than normal. Reflective stone quadruples the radius of illumination of any light source brought inside.
Wizard Fire: The rarest and most wondrous of natural illuminations in the Realms Below, wizard fire consists of dancing sheets of dim light, like the northern lights of the surface world. Though it is only as bright as starlight, wizard fire is weird and beautiful.
ECOLOGY
Besides its many predatory races and monsters, the Underdark is also home to a variety of natural animals that live out their lives normally below the ground. These animals include (but are not limited to) bats, crickets (and cricket droppings and eggs), eyeless cavefish and crayfish, springfish, salamanders, rats, flies and gnats, and spiders. Additionally, it is not unusual for creatures in the Upperdark to encounter the occasional raccoon, frog, stray dog, or even lost dwarf, elf, or other representative of a surface race who has accidentally fallen down a deep shaft or well.
PLANTS AND FUNGI
Plants of one kind or another are the beginning of any food chain. By organizing inorganic minerals and capturing the energy of sunlight, plants create food that animals of all kinds depend on. Since plants in the Underdark do not have access to sunlight, they must make food by other means. Thus, most take very different forms than the green plants of the surface world. Most of the Underdark’s plant life consists of a tremendous variety of fungi. Fungus normally requires some amount of detritus or decaying material to thrive. So where does the fungus find its food? The answer is simple: magic. The natural magical radiation of the Underdark and its various planar connections support many weird fungal growths, as well as lichens, mosses, and other simple plants, whose existence would otherwise be impossible. In effect, faerzress is the sunlight of the Underdark, forming the basis of the subterranean food chain. Underdark regions particularly rich in faerzress or planar energies have been known to support fantastic forests of pale, gnarled trees or crystalline plants. These growths are completely adapted to their lightless, hostile environment.
Surprisingly, however, green plants are not entirely absent from the Underdark. Some caverns illuminated by particularly bright radiant crystals can actually support green plants. Caves with this sort of dazzling illumination might be filled with grass, moss, ferns, creepers, or even small trees. Any such place is a treasure beyond price in the Underdark, and it is certain to be guarded by deadly spells, monstrous guardians, or both.
Barrelstalk: Stout as a hogshead of ale, the barrelstalk is a large, cask-shaped fungus that grows up to 8 feet in height and 5 feet in diameter. Its outer layers are tough and woody, but its inner flesh is edible, and its center is filled with a reservoir of water (usually from 20 to 50 gallons) that can be tapped and drained. The inner flesh turns black and poisonous when barrelstalk begins producing spores, which happens after ten years of growth.
Bluecap: The grain of the Underdark, bluecap fungus is inedible to humanoids, but its spores can be ground to make a nutritious, if bland, flour. Bread made from bluecap flour is usually known as sporebread. Bluecap seems to do well with or without faerzress, and most Underdark humanoids cultivate it.
Cave Moss: Found only in faerzress-rich regions, cave moss is inedible to humanoids, but it is a favorite grazing food of some
giant vermin, as well as rothé.
Fire Lichen: Pale orange-white in color, fire lichen thrives on warmth, so it grows in regions of geothermal heat or near connections to the Elemental Plane of Fire. Fire lichen can be ground and fermented into a hot, spicy paste, which is often spread on sporebread to give it flavor. Duergar ferment fire lichen into a fiercely hot liquor.
Luurden: Luurden, or bloodfruit, is a rare tree that grows only in areas of strong faerzress. The barren branches of this pale, gnarled tree seem more dead than alive, but once every 3 to 4 years, it produces a small amount of bitter red fruit that is used to make rare Underdark wines and elixirs.
Ripplebark: A shelflike fungus that resembles nothing so much as a mass of rotting flesh, ripplebark is surprisingly edible without any special preparation, although it tastes much better if cooked properly. Ripplebark grows naturally in living caves.
Sussur: Rare and magical, the so-called “deeproot” tree is found only in the largest of caverns. It can grow to a height of 60 feet, and its branches are long and gnarled, with banyanlike aerial roots. Few leaves grow on the sussur; it exists almost entirely on faerzress and is often found in caverns where wizard fire is prevalent. a sussur treecan drink in magic from its environs, so most sussurs are surrounded by antimagic fields that extend for hundreds of feet.
Waterorb: This bulbous fungus is aquatic. It grows in boulderlike patches underwater wherever the water deposits detritus.
Zurkhwood: This giant mushroom can reach a height of 30 to 40 feet. Its large spores are edible with proper preparation, but zurkhwood is mportant primarily because its stalks are hard and woody. Zurkhwood is one of the very few sources of timber (or anything like it) in the Underdark, and many items that would be crafted from wood in the surface world are fashioned from zurkhwood in the Realms Below.
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.
LIGHT
Except for any lanterns that characters bring into the caves, the Underdark is absolutely dark. Coupled with the tomblike silence of most passages, absolute darkness can unnerve even the most experienced caver. Thus, extra lights and oil (or magical means of illumination) are important for any cave trip.
ARTIFICIAL ILLUMINATION
Halflings, humans, and other surface dwellers without darkvision must absolutely carry some form of light with them in order to navigate the Underdark. While torches or lanterns are feasible for relatively short trips, a journey of more than a few days might require dozens of torches and oil flasks, making nonmagical light impractical for long expeditions.
The best and most efficient means of providing light in the Underdark is to use minor alchemical or magical items, such as sunrods or continual flame torches. A sunrod is small, light, and long lasting, capable of providing illumination in a 30-foot radius for 6 hours. A party of explorers could easily carry several dozen sunrods, which would provide enough light for many days of travel. At 2 gp apiece, an investment of 100 gp or so is well worth the money.
The continual flame torch is potentially cheaper, since the material component costs only 50 gp and the item lasts forever if not destroyed. However, such a torch only illuminates a 20-foot radius.
NATURAL ILLUMINATION
While most of the Underdark is exactly that, some locales possess sources of natural illumination.
Luminescent Growths: Rare forms of lichen, fungi, and moss are bioluminescent. In sufficient quantities, these growths can illuminate large caverns. Most bioluminescent growths are quite dim, so a cavern illuminated by glowing moss or fungi is typically as dark as starlight, although some particularly bright regions might be equal to moonlight.
Molten Rock: Areas with exposed pools or streams of magma are illuminated by the dim, ruddy glow of the molten rock. The glare of molten rock is typically equal to moonlight.
Radiant Crystal: Some rare rocks of the Underdark are naturally radiant, ranging in brightness from starlight to full daylight, although daylight equivalence is quite rare. The great vault of Deep Imaskar is roofed with radiant crystal that is as bright as weak surface daylight.
Reflective Stone: While not naturally luminescent, caverns made partially of reflective stone can be much more easily illuminated by small light sources than normal. Reflective stone quadruples the radius of illumination of any light source brought inside.
Wizard Fire: The rarest and most wondrous of natural illuminations in the Realms Below, wizard fire consists of dancing sheets of dim light, like the northern lights of the surface world. Though it is only as bright as starlight, wizard fire is weird and beautiful.
ECOLOGY
Besides its many predatory races and monsters, the Underdark is also home to a variety of natural animals that live out their lives normally below the ground. These animals include (but are not limited to) bats, crickets (and cricket droppings and eggs), eyeless cavefish and crayfish, springfish, salamanders, rats, flies and gnats, and spiders. Additionally, it is not unusual for creatures in the Upperdark to encounter the occasional raccoon, frog, stray dog, or even lost dwarf, elf, or other representative of a surface race who has accidentally fallen down a deep shaft or well.
PLANTS AND FUNGI
Plants of one kind or another are the beginning of any food chain. By organizing inorganic minerals and capturing the energy of sunlight, plants create food that animals of all kinds depend on. Since plants in the Underdark do not have access to sunlight, they must make food by other means. Thus, most take very different forms than the green plants of the surface world. Most of the Underdark’s plant life consists of a tremendous variety of fungi. Fungus normally requires some amount of detritus or decaying material to thrive. So where does the fungus find its food? The answer is simple: magic. The natural magical radiation of the Underdark and its various planar connections support many weird fungal growths, as well as lichens, mosses, and other simple plants, whose existence would otherwise be impossible. In effect, faerzress is the sunlight of the Underdark, forming the basis of the subterranean food chain. Underdark regions particularly rich in faerzress or planar energies have been known to support fantastic forests of pale, gnarled trees or crystalline plants. These growths are completely adapted to their lightless, hostile environment.
Surprisingly, however, green plants are not entirely absent from the Underdark. Some caverns illuminated by particularly bright radiant crystals can actually support green plants. Caves with this sort of dazzling illumination might be filled with grass, moss, ferns, creepers, or even small trees. Any such place is a treasure beyond price in the Underdark, and it is certain to be guarded by deadly spells, monstrous guardians, or both.
Barrelstalk: Stout as a hogshead of ale, the barrelstalk is a large, cask-shaped fungus that grows up to 8 feet in height and 5 feet in diameter. Its outer layers are tough and woody, but its inner flesh is edible, and its center is filled with a reservoir of water (usually from 20 to 50 gallons) that can be tapped and drained. The inner flesh turns black and poisonous when barrelstalk begins producing spores, which happens after ten years of growth.
Bluecap: The grain of the Underdark, bluecap fungus is inedible to humanoids, but its spores can be ground to make a nutritious, if bland, flour. Bread made from bluecap flour is usually known as sporebread. Bluecap seems to do well with or without faerzress, and most Underdark humanoids cultivate it.
Cave Moss: Found only in faerzress-rich regions, cave moss is inedible to humanoids, but it is a favorite grazing food of some
giant vermin, as well as rothé.
Fire Lichen: Pale orange-white in color, fire lichen thrives on warmth, so it grows in regions of geothermal heat or near connections to the Elemental Plane of Fire. Fire lichen can be ground and fermented into a hot, spicy paste, which is often spread on sporebread to give it flavor. Duergar ferment fire lichen into a fiercely hot liquor.
Luurden: Luurden, or bloodfruit, is a rare tree that grows only in areas of strong faerzress. The barren branches of this pale, gnarled tree seem more dead than alive, but once every 3 to 4 years, it produces a small amount of bitter red fruit that is used to make rare Underdark wines and elixirs.
Ripplebark: A shelflike fungus that resembles nothing so much as a mass of rotting flesh, ripplebark is surprisingly edible without any special preparation, although it tastes much better if cooked properly. Ripplebark grows naturally in living caves.
Sussur: Rare and magical, the so-called “deeproot” tree is found only in the largest of caverns. It can grow to a height of 60 feet, and its branches are long and gnarled, with banyanlike aerial roots. Few leaves grow on the sussur; it exists almost entirely on faerzress and is often found in caverns where wizard fire is prevalent. a sussur treecan drink in magic from its environs, so most sussurs are surrounded by antimagic fields that extend for hundreds of feet.
Waterorb: This bulbous fungus is aquatic. It grows in boulderlike patches underwater wherever the water deposits detritus.
Zurkhwood: This giant mushroom can reach a height of 30 to 40 feet. Its large spores are edible with proper preparation, but zurkhwood is mportant primarily because its stalks are hard and woody. Zurkhwood is one of the very few sources of timber (or anything like it) in the Underdark, and many items that would be crafted from wood in the surface world are fashioned from zurkhwood in the Realms Below.