The description of the Abyss varies between different schools, authors and eyewitness accounts. This can be viewed as the Abyss changing, or as the result of misinformation spread by the demons themselves, and of misunderstandings by those who study them.

One description of the Abyss presents it as a region of intense, extreme, and unforgiving climates, with layers consisting of overwhelmingly fierce desert sandstorms; explosively unstable volcanic activity, boiling lava, and molten rock; blinding, sub-zero Arctic glaciers; bottomless oceans filled with enormous leviathans; nauseatingly putrid environments saturated with disease-causing fungi; and the endless, existential void of infinite space.

Like other outer planes, the Abyss is spatially infinite.

The Abyss links via the Astral Plane, to Toril, the Material Plane. A number of portals directly connect it with the Barrens of Doom and Despair, Clangor, and on occasion, with, Deep Caverns and The Fated Depths. The Styx flows through the Abyss and the other lower planes, allowing travellers access to those planes by navigating the river.

The Abyss is said to consist of an infinite number of layers, though the total number is also quoted as 666. Layers are numbered based upon order of discovery by various personalities, sometimes documented by the Fraternity of Order. Discrepancies in layer numbers can be explained as catalogues that have been compiled by different sources.

It is impossible to know with any certainty whether layers are actually arranged in this precise order. A useful metaphor is a deck of playing cards shuffled and then tossed down so they are piled together loosely, randomly, and sometimes not at all.

A list of layers includes:

1 – Pazunia (also known as The Plane of Infinite Portals or The Palace of 1001 Closets) has been described as an infinite plane with only three types of distinct features:
The river Styx flowing through it (as it does through the top layers of other evil planes).
Large sinkholes which connect to other layers of the Abyss, some were drilled intentionally by ancient demons during the Abyss’ original exploration. The largest of these holes is the Grand Abyss.
Iron Fortresses which guard the physical bodies of Demon Princes when they leave the Abyss to travel astrally.
2 – Driller’s Hives, realm of Tharzax the Chattering Prince.
3 – The Forgotten Land, realm of Zzyczesiya the Ungrasped.
4 – The Grand Abyss, a bottomless, nigh-infinite canyon that contains portals to virtually every other layer in the Abyss.
5 – Wormblood
6 – Realm of a Million Eyes, home to the Great Mother, Princess of Beholders.
7 – Phantom Plane, realm of the demon lord of the lizard kings, Sess’Innek.
8 – The Skin-shedder, realm of Volisupula the Flensed Marquesse.
9 – Burningwater
11 – Molrat
12 – Twelvetrees
13 – Blood Tor,5 realm of the goddesses Beshaba and Umberlee
14 – The Steaming Fen, realm of the Queen of Chaos.
17 – Death’s Reward, realm of Abraxas the Unfathomable.
21 – The Sixth Pyre, realm of Kardum, Lord of Balors.
23 – Iron Wastes, home to Kostchtchie, demon Prince of frost giants.
27 – Malignebula,6 realm of the Abyssal lord Lissa’aere the Noxious.
32 – Sholo-Tovoth: The Fields of Consumption, realm of Turaglas the Ebon Maw.
45 to 47 – these three layers make up Azzagrat, the realm of the demon prince Graz’zt, the rival of Demogorgon. Other sources list these as layers 42 to 44.
49 – Shaddonon, realm of the demon lord Rhyxali, Princess of Shadow.
52 – Vorganund
66 – The Demonweb Pits, home of Lolth, queen of spiders and principal deity of evil drow.
67 – The Heaving Hills (Verrangoin Realm)
69 – The Crushing Plain
70 – The Ice Floe
71 – Spirac, hunting grounds of the demon lords.
72 – Darklight, realm of Nocticula the Undeniable.
73 – The Wells of Darkness, currently serve as the prison of several demon lords such as Shami-Amorae, Ansitif and Ebulon.
74 – Smargard, home to Merrshaulk the yuan-ti deity and Ramenos the bullywug deity. Also contains The Viper Pit (Sseth’s realm), and the Silent Temple.
77 – The Gates of Heaven, realm of Munkir and Nekir.
79 – The Emessu Tunnels, realm of Anarazel the Daring Darkness.
88 – The Gaping Maw (or Brine Flats or Abysm), home to Demogorgon, Prince of Demons, one of the highest-ranking demons in the abyss.
89 – Shadowsea, oceanic realm of the demon lord Dagon, Prince of the Depths.
90 – The Guttering Cove, realm of Ilsidahur the Howling King.
92 – Ulgurshek
111 – The Mind of Evil, realm of Sch’theraqpasstt the Serpent Reborn.
113- Thanatos, the realm of Orcus, demon prince of the Undead. Some quote this as layer #333 or #133.
128 – Slugbed, realm of the Abyssal lord Lupercio the Baron of Sloth.
137 – Outcasts’ End, realm of Azazel, Prince of Scapegoats.
142 – Lifebane, realm of the god Chemosh from the Dragonlance setting.
148 – Torrent
176 – Hollow’s Heart, realm of the demon lord Fraz-Urb’luu, which, due to his magical illusions, appears to be flat, colorless, and featureless to the human eye.
181 – The Rotting Plain, realm of the troglodyte god Laogzed.
193 – Vulgarea, realm of the foxwoman goddess Eshebala.
222 – Shedaklah (aka The Slime Pits), home to Juiblex demon Prince of Slimes, and Zuggtmoy, Demon Queen of Fungi.
223 – Offalmound, former realm of the dead god Moander
230 – The Dreaming Gulf, a windy realm home to the dreams of dead gods.
241 – Palpitatia, realm of the bugbear gods Grankhul and Skiggaret.
245 – The Scalding Sea
248 – The Hidden Layer, realm of Eltab.
274 – Durao (gateway layer), mustering ground for the armies of the Abyss as they prepare for battle in the Blood War.
297 – The Sighing Clifs, realm of the Abyssal lord Lady Lynkhab.
300 – Feng-Tu, realm of the Chinese gods Tou Mu and Lu Yueh.
303 – The Sulfanorum
313 – Gorrison’s Grasp, site of Illssender’s Tower
333 – The Broken Scale, realm of the god Hiddukel
340 – The Black Blizzard
357 – The Arc of Eternity, realm of Eldanoth the Bloodless Scion.
377 – Plains of Gallenshu
399 – The Worm Realm, realm of the gnome god Urdlen.
400 – Woeful Escarand (Nalfeshnee Realm), a court at which newly arrived larvae and sometimes other demons are judged
403 – The Rainless Waste, site of Mal Arundak, the City of Confusion
421 – White Kingdom, ruled by the King of Ghouls, once a vassal to Orcus and Yeenoghu, but is now a free agent.
422 – The Seeping Woods, ruled by Yeenoghu, Demon Prince of Gnolls
423 – Galun-Khur
452 – Ahriman-abad, realm of Ahrimanes, Chief of the Cacodaemons.
471 – Androlynne, realm of Pale Night.
487 – Lair of the Beast and Mansion of the Rake, realm of the vampire god Kanchelsis.
489 – Noisome Vale, ruled by the balor Tarnhem.
493 – The Steeping Isle, realm of Siragle the Ineffable.
499 – Carroristo
503 – Torremor, realm of the demon lord Pazuzu.
507 – Occipitus, former realm of Adimarchus, the demon prince of madness.
518 – *Melantholep *possible name of the nesting grounds of the chole dragons
524 – Shatterstone, realm of the ogre god Vaprak.
531 – Vudra, realm of the giant marilith Shaktari, the Queen of Poison.
558 – Fleshforges, realm of Dwiergus the Chrysalis Prince.
566 – Soulfreeze, realm of Aseroth the Winter Warlock.
570 – Shendilavri, realm of the demon lord Malcanthet, Queen of the Succubi.
586 – Prison of the Mad God, realm of the derro god Diinkarazan.
597 – Goranthis, realm of Socothbenoth the Persuader.
600 – Endless Maze, the realm of Baphomet, demon Prince of Minotaurs. The demoness Pale Night resides here as well.
601 – Conflagratum, realm of the Abyssal lord Alzrius, Lord of Infernal Light.
628 – Vallashan, a layer designed to allow temporary victory to conquering armies of good alignment, only to then corrupt the conquerors and turn them against themselves
643 – Caverns of the Skull, realm of the Black Earth Mother Kali, the goddess of destruction.
651 – Nethuria, realm of Vucarik, Consort of Chains.
652 – The Rift of Corrosion
663 – Zionyn, realm of the demon lord Obox-ob, Prince of Vermin.


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