HistoryShortly after Mahri Nui sunk into the ocean, molten magma cooled forming The Cord and linking the two islands together. It eventually became home to various Rahi both land and marine and the Zyglak as well. When the Toa Inika traveled down the The Cord they encountered the Zyglak and fought them. However a giant Venom Eel from outside shattered a part of the The Cord after hearing the noise in side thinking it was food. The Zyglak and land Rahi were presumingly killed but the Toa Inika were saved when the Ignika turned them into water-breathing Toa Mahri. The Toa Mahri later led the population of Mahri Nui to the surface of Voya Nui via the The Cord and later destroyed it with their Cordak Blasters to insure that Voya Nui returned to it's original position on the Southern Continent.
The inside of The Cord consisted of the flooded or partially flooded tunnels and caverns who were home to dangerous Rahi and Zyglak.