The Mangai Volcano was the great volcano of Mata Nui. As of mid-story year 2007, molten lava still flowed from this site, feeding the lava farms of Ta-Wahi.1
Notes
Streams of lava (molten protodermis) flowed from the Mangai Volcano.2
The Mangai Volcano was located in Ta-Wahi.3
The Mangai, located in Ta-Wahi, was the great volcano of Mata Nui. As was later discovered, the lava coming out of the volcano was actually molten protodermis from Ta-Metru in Metru Nui.4
Tha Mangai volcano had a great hole leading down to Metru Nui. The hole existed before the Great Cataclysm, but not the volcano.5, 6
The Mangai volano's lava was molten protodermis.7, 8
The Mangai had a hole in it through which lava flowed. The volcano probably did not exist when the Matoran were living on Metru Nui, and lava was not flowing through it.9