Thras

Thras is partially submerged continent located west of Tamriel. It is known as the Coral Kingdom of Thras or simply the Coral Kingdom. Thras is home to notorious, slug-like creatures: the Sloads. They are an antagonizing power that terrorized the Summerset Isles since before recorded time. Sloads are known as masters of necromancy, and have consistently been sending sea-monsters and laying siege on Skywatch on the coasts of the Isles. For all the attacks and devastation coming from Thras, very little is known about the land itself.

History
In year 2260 of the First Era, the Thrassian Plague decimated Tamriel's population, battering it to the point where over half the population was killed by he disease.It had been created by the Sloads, and was their most devastating attack on Tamriel in recorded history.

When the Redguards came to Hammerfell from Yokuda, they brought with them a tradition of burying criminals off their shores, to prevent their evil spirits from disturbing the living. The Sloads used the graveyards and transformed them into laboratories for their necromantic rituals. The Redguards pushed back the invaders, but there have been reports of Sloads living on the island of Stros M'kai even in the Third Era.

Geography
The first maps made by cartographers that traveled to Thras, and returned from the journey, describe the continent being made up of sixteen smaller islands in a semicircle, like a partially submerged coral atoll. Over the centuries, spies created new maps of Thras, but the amount and size of the islands varied, suggesting the Sloads have a volatile kingdom which fluctuates in land mass, either by the tides or some other, less natural means. The biggest island, Agonio, seems to be the most stable, though later maps depict it significantly larger then earlier.