Origin: Maori (Māori) Mythology, New Zealand
Haumia was the taniwha who lived in the Manukau Harbour.  He had enormous power and associated with the Waikato peoples, who he protected, and kept several medium among the tohunga, or priests.  Haumia is best known for a particular incident that took place with the taniwha of the neighboring Hauraki people, Ureia.  Ngatimaru, a leader, claimed this taniwha as a pet. 
Haumia contacted one of the tohunga to tell the people that Ureia had to be killed. The plot included Haumia luring the other taniwha back to the harbor, where he would meet his fate at the noose held by every sturdy person that could be found. 
Haumia then swam to Hauraki Harbour to pay a visit to Ureia, with plans of inviting him back to Manukau.  As he approached the neighboring taniwha, Ureia asked, "What're you come here for? Did you bring food from your country for me?" 
Cunningly, Haumia replied, "Aye, absolutely, there is plenty to eat there and plenty of richness besides that." 
Ureia, curious but still reserved, asked, "Well, what are the riches of your country?" 
"The feathers of the huia and the kotuku, the scented leaves of the raukaiva, and the perfume that is distilled from the plant taramea. Besides this, there is an abundance of kopura as well as of the manehu and taiviri tree."  Haumia spared no tale, claiming that a great feast had been prepared with these splendid gifts. 
"Indeed!" exclaimed Ureia, now excited at the invitation. "Well, then, lead me to your country and show me its treasures." 
Haumia asked him to go first to see his country, and as soon as Ureia moved out of his cave, Haumia swooped down and shut the cave door completely closed.  Despite Ureia's discomfort with this particular action, Haumia swam ahead, and he followed, thinking no harm would come to him. 
Haumia moved safely into the harbor with his companion directly behind him. As soon as Ureia had entered the threshold, however, a rope suddenly tightened around him. The sturdy people from the area had taken it up, and with a great deal of effort that hauled the unfortunate taniwha out of the water and suffocated him. 
In other versions, on one side of the Manuka Harbour a thousand men stood, and the other side had equally as many at the ready. They had completed weaving a snare, ordered to by Haumia through the tohunga.  The tohunga (priests) recited prepared chants at the tuahu (tūāhu), or shrine, while the men tightened the ropes around the poor, unsuspecting taniwha.  The Waikato people knew a great deal about slaying taniwha, for there are some taniwha that kill without provocation. The Waikato tohunga had a great many incantations that, because the taniwha did not know them or their power, could help weaken and capture any one of the water beasts. 
When the two taniwha arrived outside of the entrance to the harbor, Haumia, through the tohunga, informed the people to stand at the ready and to remind them that all pulling needs to be done in unison.  When Ureia's neck passed through the snare, every man pulled together, catching the taniwha and pulling him up and out of the water. Suspended and helpless, Ureia struggled as hard as he could against the snare. 
20. It was on the ebb-tide he was caught. On the change of tide he was still struggling and alive: still so on the changes of the tides, and on four ebb-tides and four flood-tides, he struggled, and then died.
21. Great was the wonderment of the people by whom Ureia was slain. Now this people was a taniwha-slaying people - Ureia was the only taniwha who lived thus so long, for four ebb-tides and for four flood-tides. However, such was the death whereby Ureia died.
-- Geo Graham in "Some Taniwha and Tupua" 
This unprovoked action on so great a guardian and symbol did not go unanswered upon. Armies from Hauraki, who once held Ureia as their guardian, attached the peoples of Tamaki (Tāmaki), Manukau, and Waikato in response to Haumia's treachery. The conflict escalated into war. 
After this incident, the people of Hauraki became suspicious of the Waikato people. Since Haumia, their guardian, had wisely and cunningly lured Ureia to danger with a feast, caution is now taken at the welcome of the kingship of Waikato. Ureia left for a feast and was killed for his trust; likewise, the Hauraki thought that the Waikato people would act as their taniwha did.