In Maori legend, Horomantangi or Ihu-Maatatao was one of the monstrous races of the Taniwha. It had the form of a giant lizard. He created the giant Karapiti blowhole where a grey geyser gushes out. He has the reputation of overturning boats.
John and Caitlin Matthews, The Element Encyclopaedia of Magical Creatures, 2013, Horomantangi, p 238