A famous tāniwha, or water monster, of Lake Taupō, North Island. It is a reptile goblin who resides in an underwater cave on the reef on the north-east side of Motutāiko Island. From time immemorial Horo-matangi had been the custodian of the mana of the lake, aided in all his acts by his familiar, the man tāniwha, Ati-a-muri, who may be seen paddling his canoe in the dusk of the evening on the look-out for unwary strangers.
- Gudgeon, W. E. (1905). "Maori Superstition." Journal of the Polynesian Society 14:167-193, p. 189.
- Tregear, Edward. (1891). Maori-Polynesian Comparative Dictionary. Wellington: Government Printer, p. 85.
- White, John. (1885). "Maori Customs and Superstitions." In T. W. Gudgeon, History and Doings of the Maoris from 1820 to 1840. Auckland: Brett, pp. 97-225, p. 119.