”... a place with a black sky and a strange, small white sun that hung on the horizon ... Flames hovered nearby ... Like the tips of candles floating in the air and moving with the wind ... An endless dark sea, except it wasn't wet. It was made of the small beads, an entire ocean of tiny glass spheres
Geographically, Roshar in the Cognitive Realm appears like an inversion of the continent in the Physical Realm, with its inland seas corresponding exactly to the shape of the land of Roshar. The "seas" are made of tiny dark glass beads that represent objects that exist in the Physical Realm. These beads are bean-sized, or slightly larger than a fingernail. There are spren that look like "little green and orange people, only a few inches tall" climbing around the spheres. When asked if this is the general rule, Sanderson said "there are places in Shadesmar that are different, and some are the same."
Living things manifest on Roshar's Cognitive Realm as flames. If the person is strongly influenced by Odium (and presumably certain other Shards), the flame turns red. A flame vanishes when the person represented by it dies.
”She stepped up beside the bead statue, noting for the first time the strange clouds overhead. They seemed to form a narrow ribbon of highway, straight and long, pointing toward the horizon.
The sky on Roshar's Shadesmar is black, with strange cloud formations and a small, cold sun. The land, which corresponds to bodies of water on the Physical Realm, appear to be made of obsidian. Trees made of crystal grow on this land.
Land masses appear as lakes or oceans of glass beads. The beads represent "souls of objects." 
The Shadesmar Map
The map of Shadesmar found in The Way of Kings labels several areas in the Cognitive Realm, including regions called "Expanses" that are outside of Roshar. If you walk far enough (likely for days) in the direction of one of those Expanses, you can arrive on another world. The areas labeled are as follows:
- Expanse of the Vapors: This area is confirmed to be Scadrial.
- Expanse of the Densities: This area is confirmed to be Sel.
- Expanse of Vibrance: This expanse's name was hidden behind the map's title.
- Expanse of the Broken Sky
- Nexus of Imagination
- Nexus of Truth
- Nexus of Transition
- Sea of Regret
- Sea of Souls
- Sea of Lost Lights
- Main article: Spren
Spren are Splinters that reside mainly in the Cognitive Realm of Roshar. Each spren represents an idea or concept, and are described as ideas that gained life.
There is great variety among spren, both in appearance and in cognitive levels. Some spren are intelligent enough to build their own civilizations and live on cities in Shadesmar, while others are more like animals. Most of these spren appear and behave differently when they transition to the Physical Realm.
Access and Use
The ardents in Roshar are aware of Shadesmar, and have used fabrials that allow them to Soulcast objects through it. There are also people whose bond with certain types of spren grants them access to Shadesmar. One type of such a spren, called a Cryptic, is described by Shallan as
”a figure with a sharp, angular symbol hovering above its collar instead of a head
For a member of the Order of Lightweavers to be granted entrance to Shadesmar, the person must have spoken enough truths about themselves to their bonded Cryptic. In Shallan's case, the Cryptic she calls Pattern no longer required truths for her to enter Shadesmar after she confessed her darkest secret. Pattern helps Shallan Soulcast by acting as a translator between her and the objects represented by the glass beads.
Both Orders can use the glass beads in Shadesmar to form various structures that can be used there. For example, Jasnah can create a raft out of Shadesmar beads that she could stand safely on. While trapped in Shadesmar, Shallan uses this ability on several occasions. While attempting to use the Thaylen City Oathgate, she makes a wall physically appear there, rather than just being made of beads. This is called manifesting, and is described as being dangerous by Captain Notum.
It seems likely that at the least, Willshapers also have some direct connection to Shadesmar.
Azure, Shallan, and Kaladin all get impressions from the beads they pick up while in Shadesmar, so it should be reasonable to say that any Invested person can manifest objects there. Adolin, not being an Invested person, gets only the vaguest impressions of the objects the beads represent.
Ingesting the beads and then moving to the Physical Realm would not be good for a person.
Stormlight (or an alternative source of Investiture) is needed in order to control objects in Shadesmar, as well as for Soulcasting. Traveling there without sufficient Stormlight is considered to be perilous.
When Shallan tries to use the corrupted Oathgate in Kholinar it transports all those in the control room to Shadesmar. Azure tells them that the way to get out is to go to where the Horneater Peaks are in the Physical Realm and use Cultivation's Perpendicularity.
- Barnes and Noble Book Club Q&A
— Arcanum - 2009-07-08#
- Words of Radiance San Diego signing
— Arcanum - 2014-03-04#
- Words of Radiance Omaha signing
— Arcanum - 2014-03-13#
- The Way of Kings chapter 45 #
- Oathbringer Portland signing
— Arcanum - 2017-11-16#
- Oathbringer chapter 89 #
- Words of Radiance Omaha signing
— Arcanum - 2014-03-13#
- Oathbringer chapter 116 #
- Words of Radiance prologue #
- Words of Radiance chapter 7 #
- Orem signing 2014
— Arcanum - 2014-12-06#
- Oathbringer San Francisco signing
— Arcanum - 2017-11-15#
- Rithmatist Omaha signing
— Arcanum - 2013-05-17#
- Words of Radiance chapter 1 #
- The Way of Kings interlude I-8 #
- The Way of Kings chapter 70 #
- Skyward Chicago signing
— Arcanum - 2018-11-16#
- Oathbringer chapter 87 #
- Oathbringer chapter 93 #
|Shards||Ambition · Autonomy · Cultivation · Devotion · Dominion · Endowment · Honor · Odium · Preservation · Ruin · Survival Shard|
|Planets||Ashyn · Braize · First of the Sun · Nalthis · Obrodai · Roshar · Scadrial · Sel · Taldain · Threnody · Vax · Yolen|
|Terms||Adonalsium · Sliver · Splinter · Realmatic Theory · Investiture · Connection · Identity · Fortune · Intention · Perpendicularity · Spiritweb · Resonance|
|Worldhoppers||Hoid · Khriss · Nazh · Iyatil · Mraize · Vasher · Vivenna · Galladon · Demoux · Baon · Felt · Marsh · Nightblood|
|Other||Seventeenth Shard · Ire · Shattering · Letters · Silverlight|