It had buildings jutting from rock and castles hanging from cables, and towers on the rim of the island that appeared to be made of spun glass.
Umbriel was powered by a new version of the ingenium. People killed below Umbriel were used to power the ingenium, to sustain the floating city and thereby satisfy a pact made with Umbra.
Umbriel invaded Tamriel in 4E 48, first appearing far off the coast of Black Marsh south of Lilmoth. It was summoned there by the rogue Hist of Lilmoth, which was able to communicate to the similar trees native to Umbriel.:53 It traveled north to Scathing Bay and then west to the Imperial City in an attempt to free itself from Vile's realm using metaphysical power of the White-Gold Tower.
As of 4E 201 the Sleeping Tree, a strange leafless tree, was found in Whiterun Hold in Skyrim. Several legends exist about the origins of the Tree. Some say that a piece of rock was blasted from Red Mountain during the Red Year and landed in Skyrim, and the Tree grew from the resulting crater. Others, however, say that it grew from a spore that fell from a "floating island", referring to Umbriel, in which case the Tree could be one of the Hist of Umbriel. It was the source of a legal drug known as the Sleeping Tree Sap.
- Fringe Gyre - A region on a cliff on the outside edge of Umbriel, wrapping around it. It is filled with trees that seem to be related to The Hist, including one especially tall one. The trees produce what Umbriel needs, such as different types of fruit and even things like iron. Tree-tenders take care of the trees and harvest these plants.
- Ghol Manor - One of the manors of Umbriel, served by Qijne's kitchen. Lord Ghol is known to dislike boring food.
- Glass Forest - The "glass forest" is the name that Sul and Attrebus gave to a webbing of a glasslike material found at the top of the city. The glass tubules can be controlled making them move or immobilize an enemy.
- Kitchens - The Kitchens (called "vehrumasas" in Umbrielic) are where food is made for the lords and ladies of Umbriel. The lower kitchens make food for the minor lords, who have more earthly palates, while the upper kitchens work for higher lords, who require food made of spiritual essences. Qijne's kitchen, which is one of the lower parts, mainly has walls lined with ovens, with the center of the room containing pits of hot stone, counters and cabinets, and cages and baskets hanging from chains from the ceiling. One end has tables for more delicate work. Toel's kitchen, by contrast, only has one pit and oven, but plenty of red granite countertops with alchemy apparatuses, and is mostly dedicated to preparing soul essences - both for the lords of Umbriel and for the trees of the Fringe Gyre.
- Lower Middens - The Lower Middens are essentially a gigantic trash room, where the refuse from the kitchens that doesn't wind up in the sump goes and is eaten and digested by worms, likely before being used for some other function. These are split into four main middens; Bolster Midden is noted for being the midden with the "richest scent".
- Oroy Mansion - One of the manors of Umbriel, served by Qijne's kitchen. The residents were known to like burnt food.
- Prixon Palace - Served by Qijne's kitchen. The residents were known to not like their food burnt.
Umbrielans - many of whom are similar in appearance to the races of Tamriel - are born into fully-formed adult bodies and live short lives; a ten-to-fifteen-year-old Umbrielian is considered old. When Umbrielans die, their soul is recycled and reborn into a new body through the use of worm-like creatures known as proforms, though they do not retain the memories of their previous life. The language spoken on Umbriel is very similar to Ehlnofex, and, unsurprisingly, is named Umbrielic.
Hobs are a race of hairless monkey-like creatures which inhabited Umbriel. They have long arms and legs, very long, thin, delicate fingers. Their faces are described as goblinesque, with huge toothless mouths and large green eyes.:Part 1, Chapter 8
Hobs can speak very simple Tamrielic, though they seem to have their own language as well.:Part 3, Chapter 10 They were used as assistants by chefs in the kitchens of Umbriel, and were usually tasked with fetching specific ingredients. Troops of them could sometimes be found harvesting bloodball fruit in the Marrow Sump.:Part 3, Chapter 1 Supposedly, some chefs would train their Hobs to perform "unconventional" favors for them.:Part 2, Chapter 4 It was unknown whether Hobs were creatures that reproduced or grew in a normal way, or if they were grown like the other people of Umbriel.:Part 3, Chapter 10
- Umbriel — A summary of information from the Greg Keyes novels.