Nirn

Nirn is a planet referred to by otherworldly beings as the mortal plane and sometimes poetically called "Mundus" by both mortals and Daedric lords. The exact reasons and specifics behind Nirn's creation are largely uncertain. However, all agree that the deity Lorkhan and the Eight Divines played pivotal roles in the creation of the planet.

Geography

The planet has a notably large continent, Tamriel, which is where all of The Elder Scrolls activity takes place, with another similarly large continent to the east, named Akavir. The land masses are separated by the Padomaic Ocean, a massive saline body of water.
The cold, barren land called Atmora is to the north of Tamriel, which is where the Nords of Tamriel hailed from. To the west of Tamriel lies Yokuda, which was the former homeland of the Redguards of Tamriel. To the southwest of Tamriel lies Pyandonea. It is unknown if these are the only continents, as there are very few maps or globes showing all of Nirn.

Tamriel

Tamriel is geographically diverse: it has mountains, tundras, cold and hot deserts, swampy regions, grasslands, tropical rainforests, and a large volcano. The diversity of biomes is unique as the hot desert is bordered by cold mountains to the north.
Also known as "Dawn's Beauty" in the language of the Altmer, Tamriel also has an archipelago of islands called the Summerset Isles, which became the home of the Altmer, or "High Elves," after they abandoned their original homeland of Aldmeris.

Yokuda

Not much is known about Yokuda since it was nearly obliterated in an unknown cataclysmic event, but it seems to have a dull, rocky, hilly, desert landscape. It is known to be the original home to the Redguards before they rendered it uninhabitable.

Atmora

Atmora is a barren and frozen wasteland. It is this extreme cold that caused the water of the Sea of Ghosts that separates Tamriel and Atmora to become icy. This frozen land is also where the progenitors of the Nords of Skyrim, the Atmorans are originally from, although not many trips back are made.

Akavir

Next to nothing is known about the geography of Akavir. It is known that the continent is split into four warring kingdoms, each boasting its own race: Tang Mo, Kamal, Ka Po' Tun, and Tsaesci. Akavir is known to have been one of the original homes of the dragons. The Blades were originally from Akavir, where they were known as the Dragonguard, but turned to serve Reman Cyrodiil in their search for a Dragonborn.

Pyandonea

Pyandonea is the island-continent located to the far south-west of Tamriel and home to the elusive Maormer. The island consists of dense rainforests, which provide shelter for the southern water spirits. Due to its populace being primarily elves, there is speculation that Pyandonea may, in fact, be part of Tamriel.

Thras

Thras, also known as the Coral Kingdom, has been a powerful, antagonizing power against the Summerset Isles since before recorded time. The Sload may at one time have even called Summerset part of Thras.

Aldmeris

Little is known about Aldmeris, including if it still exists. The Altmer claim that this continent was the birthplace of both elves and mankind.

Lyg

A parallel version of Tamriel which can only be reached by sliding sideways in some unusual manner,[14] only being entered through its "non-cardinal" directions.