|Location||Under Kini Nui|
Mangaia was built by Teridax shortly after he was assigned to monitar the region of Metru Nui by Miserix. After the Great Rescue Teridax followed the Matoran to the island of Mata Nui and used Mangaia as his primary lair as it was located in between the two islands. Teridax infected most of the Rahi from here using infected Kanohi and also battled the Toa Mata here after they defeated his Shadow Toa and Manas. Several months later Takanuva confronted Teridax here and after brieftly merging into Takutanuva opened the gateway to Metru Nui the Matoran's original home. However in the process Teridax's body was crushed by the giant gate and his Antidermis escaped. Sometime later the Piraka came to lout the lair only to be attacked by Teridax's guards; the Manas Ko. However they escaped unharmed into the surface of Mata Nui. The Order of Mata Nui later destroyed the Energized Protodermis pool here.
Mangaia was vast and complexe and by far the largest of Teridax's many lairs. The lair consited of two central chambers, one of which housed a pool of Energized Protidermis and the gateway to Metru Nui and the other where the Toa Mata battled the Manas and the Shadow Toa. Their were also several smaller side chamber used for storage and weapon hording mainly the Spear of Fusion.