This page features content from BIONICLE Generation 1
External Image
From BIONICLEsector01

"Another enormous cavern lay before him, lit by more lightstone platforms. Dozens of stone columns stretched up to the high ceiling. Between these columns were paths made of cobblestones set into the earthen floor. Stone benches stood beside the paths, and a small, clear stream trickled through the cavern."
— Narrator, Tale of the Toa

Status Destroyed
Inhabitants Onu-Matoran
Toa Onua
Turaga Whenua (all formerly)
Population None
Position Onu-Wahi
Pronunciation oh-NOO-KOAR-oh[1]

Onu-Koro was the village of Earth on the island of Mata Nui. The village was located entirely underground, and the mines which fueled the Onu-Koro economy extended under most of the island.


Onu-Koro as seen in a Mata Nui Explorer game in 2002

The undercity of Onu-Koro was discovered and founded by Toa Whenua after the Toa Metru defeated Makuta Teridax and left Metru Nui to search for a new home for the Matoran. It was constructed by the Onu-Matoran under the guidance of Whenua, incorporating pieces of the dismantled Airships used in the Great Rescue.[2][3]

The Matoran and newly-transformed Turaga Whenua dwelt in Onu-Koro for one thousand years, always having to cope with the constant Rahi attacks unleashed by Teridax, and clinging to the hope of the Toa Mata coming to save them.

Onu-Koro as it appears in the Mata Nui Online Game

After a thousand years, their hopes came to fruition, and Onepu was the first to witness Toa Onua when he arrived in Onu-Koro's main plaza. The amnesiac Toa of Earth was brought to Turaga Whenua, who helped inform him of their plight and of Onua's destiny.

Around this time, an impenetrable layer of rock was unearthed in the Great Mine, impeding the Miners. In addition to that, many problems were brought up; a lava flow blocked the path to the Cavern of Light, leading to a shortage of Lightstones, and, because of this, Rahi attacks increased. Takua helped solve these problems, and later discovered that the impenetrable layer of rock was a sundial, concealing a secret entrance to the Mangaia. The village was barred in preparation for battle with Rahi as the Toa battled Teridax.

A sculpture in Ko-Wahi which could access Onu-Koro

After the Bohrok were awakened and started to level the island, Nuhvok attacked the village, trying to destroy columns in a cavern, in an attempt to cave Onu-Koro in. However, Onua was able to trick them into retreat by using their assignment against them and creating a trench around one of the last columns. Shortly afterward it was attacked and flooded by Gahlok, but Nuparu helped drive them off with his new invention, the Boxor.

Following the Toa Mata's transformation into Toa Nuva, Onua's Nuva Symbol appeared in Onu-Koro. Shortly afterward, it was stolen by a Lehvak-Kal,[4] stripping Onua of his Elemental Powers. The Nuva Symbol was returned to the village after the Bohrok-Kal were defeated by the Toa Nuva.

The village was later severely damaged by the Rahkshi Turahk, Kurahk, and Vorahk, and was deserted by the Matoran when they returned to Metru Nui. It was later destroyed by the reawakened Bohrok swarms and the location wiped from existence by Mata Nui's awakening.


Onu-Koro was located in Onu-Wahi, chiefly residing in a massive cavern. Very little of it resided on the barren surface, as the Onu-Matoran were sensitive to bright sunlight. The village could be reached via a vast labyrinth of Matoran-made tunnels extending across the island, with known entrances opening at Ta-Koro, Po-Wahi, Ko-Wahi, Le-Wahi and the nearby landmark of the Papa Nihu Reef. Many of these served as highways, allowing traders from other villages to sell their wares at Onu-Koro's famous bazaar, which led to the earth village becoming a major center of commerce on Mata Nui. Other tunnels connected to massive mines extending deep into the earth, which was abundant with valuable resources like ore, Protodermis and the Lightstones that illuminated the Onu-Matoran's subterranean home. The villagers themselves were most commonly miners and engineers, and were led by Turaga Whenua. In the center of the village plaza resided the Onu-Suva, the Great Hall where Whenua resided,[5] and a pit used for the Great Takara.[6][3]

The Ussal Crab Stables

Onu-Koro's military was the Ussalry, who are led by Onepu and ride Ussal as their steed of choice. The docile, crablike Rahi are popular pets among Onu-Matoran, and played integral roles in many aspects of life in Onu-Koro, from mining to the village's most popular sport, the Great Ussal Race. Tamed Ussal often rested and were treated in stables, which have since been vacated.

Wild Ussal also called the region home, in addition to several other Rahi, which were often nocturnal. Notable among these were the ratlike Kuma-Nui and the scorpion-like Kofo-Jaga. The latter was particularly feared by Onu-Matoran for their aggressive and territorial nature, and stumbling upon a Kofo-Jaga nest became such a common mining hazard that Turaga Whenua often had to use his Drill of Onua to detect them before deeming a new area safe for digging.



Onu-Matoran were the primary residents of Onu-Koro. Here, the Matoran performed day-to-day activities which mainly consisted of mining and digging. Due to their sensitivity to bright light, the Onu-Matoran were unable to stay on the surface for too long. Likewise, the Matoran of the other five villages were unable to see in the dark as well as the Onu-Matoran, preventing them from setting up permanent homes.

Notable Former Inhabitants

Onu-Koro plunged into darkness during a lightstone shortage


"Onu-Koro is home to Turaga Whenua. This village consists of huge caves are dug deep underground, safely hidden from the surface. Like its Toa, Onua, the people of Onu-Koro have night vision, but are sensitive to daylight. Some say that Onu-Koro is as dark as the Makuta would wish it, and care should be taken when entering this labyrinth of tunnels and caves."


Books Online Multimedia








Online Games

Video Games


Board Games

Card Games


  1. "Onu-Koro." Encyclopedia Updated, p. 107.
  2. World.
  3. 3.0 3.1 "Chapter 5: The Undercity of Onu-Koro • A Strange Discovery." Mata Nui Online Game.
  4. Makuta's Revenge. BIONICLE Chronicles 3, p. 35.
  5. "Chapter 8: Alliance • A Final Defense • The Toa Enter the Lair." Mata Nui Online Game.
  6. BIONICLE: The Legend of Mata Nui.

See also