The Great Mine was a large cavern opposite the Le-Koro and Ta-Koro highways. It was the greatest of the Onu-Matoran mines and a work place for many Onu-Matoran, including Mamru, Taipu and an Onu-Matoran prospecter wearing a noble Matatu, named Azibo. When Takua came here, they found a sundial that led to a room that had a golden mask. It was revealed later to be an entrance to Mangaia.