|Primary Residents||Matoran,Rahi,Turaga,some Bohrok Nuva|
|Location||Underneath Yudia,Mata/Metru,Gatris Nui & Nui Marsh|
The Catacombs were created when a huge team of Onu-Matoran dug huge tunnels below the North-Eastern Islands,while Po-Matoran moved extra rock and carved the walls.The Catacombs extended from Yudia Nui to as far as Nui Marsh.Some Bohrok Nuva from Nui Marsh migrated here after the tunnels were completed.
The Nui Orb Crises & Mutated Toa Yudia
When the Nui Orb Crises occurred on Yudia Nui,Toa Yudia evacuated the matoran of Yudia Nui to the Catacombs.After he died and was replaced by Mutated Toa Yudia,he came to the Catacombs and protested to the Turaga there,calling the matoran traitors and scum.He destroyed at least one village in the Catacombs in his anger,later being banished from the Catacombs.He later went to Nui Marsh and destroyed numerous villages,disappearing later.It is believed that he has teamed up with the Makuta.
The Great Cataclysm & Opehri
When the Great Cataclysm occurred,The Kralhi Opehri retreated to the Catacombs to hide from Makuta.He met some Av-Matoran here,who let him join the Order of Mata Nui.He guarded the World Schism until recently,where he moved to Nui Marsh and became it's guardian.It is believed that he has some form of Light Powers.
The Catacombs and Toa Vorvakh
When Mata Nui re-awoke, he rose and this destroyed the main tunnel of the Catacombs. Most of it flooded immediately with water.