Vaku Nui

Vaku Nui is an island south of Metru Nui, it is surrounded by a chain of islands.

History
Once, Vaku Nui was a heavenly paradise inhabited by Toa and Matoran. The Rahi were tamed, and didn't attack anyone. It is believed that the first Matoran to live there, were settlers from Artahka. They settled up villages on the island, and developing technology to live in peace. Nothing major happened.

Invasion
100 years before the Great Cataclysm occured, The High Order of Shadows invaded, crushing anyone that got in their way. The surving Matoran, Toa and Rahi fled to the chain islands, living in fear. They feared that the evil orginization would conquer these islands as well, unaware the half of them already were. The High Order of Shadows from then on used Vaku Nui as their main base of operations.

Pit of Despair
The Pit of Despair was a natural landmark, going down to the bottom reaches of the island. The Matoran would come to this Pit and despose of junk they didn't need or want. If a Matoran was upset he or she would come and empty their feelings into the Pit. It was located on the Southern end of the island and Matoran would travel all the way from the North to despose of trash.

The High Order of Shadows renovated the walls of the Pit into cells, turning it into a large prison. They spent years working on it, and made a stone staircase going all the way down.