Te Horetā, also known as Te Taniwha, was a leader of Ngāti Whanaunga, one of the Marutūāhu confederation of Hauraki Gulf and Coromandel Peninsula tribes. The names of his parents are not recorded. He may have been born about 1757, for he told James Cook he was aged about 12 when the two met on Cook's visit to Mercury Bay in November 1769. In later years Te Horetā recalled his wonder at seeing these new people. Once some of his people had returned safely from the Endeavour, he overcame his fears and ventured on board with other children. He remembered Cook's kindness to him and his companions, and Cook's puzzlement, after he asked the men to draw a chart of the coast on the deck, at the concept of reaching the Māori underworld via Te Rēinga. Cook also gave the people a double handful of potatoes. This Te Horetā believed to be the decisive introduction of the potato into the Coromandel area. The potatoes were kept for seed, and within three years Ngāti Whanaunga were able to hold a feast incorporating the new food. Te Horetā may have encountered Cook again when the Endeavour visited the Thames estuary two weeks later.
Te Horetā was probably involved in the many wars in which Ngāti Whanaunga and the Marutūāhu tribes participated in the late eighteenth and early nineteenth centuries. By about 1790 he had a daughter, Te Tahuri, who was of marriageable age. The name of Te Tahuri's mother is not known, but she had connections with Waikato and Ngāti Whatua. Through these ties Te Horetā was drawn into a series of battles, in one of which Te Tahuri and her husband were killed. He was probably also involved in the wars of Ngāti Pāoa against Te Kawerau, a tribe of the Auckland isthmus. In the mid 1790s, after the murder of a Ngāti Whanaunga leader, Ngāti Pāoa, Ngāti Maru and Ngāti Whanaunga embarked on a campaign against Ngāpuhi of the Bay of Islands. The Marutūāhu tribes twice invaded the Bay of Islands, first attacking the people of Te Rāwhiti, and then inflicting a heavy defeat on Ngāpuhi in their heartland at Puketona, in a battle known as Waiwhāriki. Some years later, about 1819, Korokoro of Te Rāwhiti, allied with Te Haupā of Ngāti Pāoa, led a war party against the Coromandel tribes to avenge these defeats. They attacked various Ngāti Maru pā as well as those in the Colville area, in the north-west of the Coromandel Peninsula, and Te Horetā's people at Waiau further south. Korokoro's party had returned to the Bay of Islands by January 1820.
In March 1820 Te Horetā appears to have joined the expedition of Te Morenga of Taiāmai, Bay of Islands, on its return from Tauranga. On 25 May 1820, with Te Morenga, he visited the British naval storeship Dromedary, which was anchored near Waikare, in the Bay of Islands. He may have played some part in convincing Captain Thomas Downie of the Dromedary's companion ship Coromandel to seek the desired cargo of kauri spars in his area, for on 7 June 1820 he returned home on the Coromandel with Te Morenga and the missionary Samuel Marsden. On his arrival he found that Te Haupā had attacked Te Puhi of Ngāti Maru, whose village at Tāruru was not far from a settlement of Te Horetā. Marsden visited both villages and described Te Puhi and Te Horetā as 'very tall, fine, handsome men'.
Te Horetā assisted Downie to obtain his cargo by directing him to the finest and most accessible stands of kauri, and the Coromandel then moved on to Te Horetā's main settlement at Waiau, which was afterwards known as Coromandel Harbour. When Marsden expressed his desire to visit Waikato Te Horetā sent a messenger to inform Waikato leaders; Marsden was persuaded to abandon this journey, however, because of the bad weather and rough terrain. After the missionary's return from his visit to Tauranga with Te Morenga he carried out his promise to make peace between Te Puhi and Te Hīnaki of Ngāti Pāoa. Marsden brought the two leaders together, but it was Te Horetā and Te Morenga who mediated between them. Te Horetā also helped to mediate between the local ariki and a subordinate leader accused of theft.
When the Dromedary entered Coromandel Harbour on 23 August Te Horetā, accompanied by all his people, performed a waiata of welcome on the deck. Ngāti Whanaunga were encouraged by the protection offered by the ships' presence to emerge from the inland valleys, to which they had fled from Ngāpuhi attacks, and they played generous hosts to their visitors. On the departure of the Coromandel in December, Te Horetā, together with Te Hīnaki and two other leaders, took the opportunity to visit Sydney, New South Wales. He was still there when Hongi Hika and Waikato arrived in May 1821 on their way home from London, England. Te Horetā had intended to visit Europe, but Hongi and Waikato dissuaded him from going because of the length of the voyage and the severity of the climate. Marsden intervened, obtaining passages to New Zealand for Te Horetā and his companions on the Westmoreland, but Te Horetā objected to this unless he was landed at Thames, fearing being killed at the Bay of Islands because of the unresolved conflict between Ngāti Whanaunga and Ngāpuhi. Marsden subsequently arranged him a passage on the Active, but it is not clear when Te Horetā and Te Hīnaki returned to New Zealand. They were still in Sydney when the Westmoreland arrived at the Bay of Islands with Hongi and Waikato on board on 11 July 1821.
Ngāti Maru tradition states that Te Horetā and Te Hīnaki were guests of Hongi at the Bay of Islands on their return to New Zealand. It is said that Hongi placed a bucket of milk before them as a test, and when they refused to take this strange food, took their rejection as an omen for his projected attacks on Marutūāhu. He lined up his muskets, naming one for each of the battles in which Ngāpuhi had been defeated by Ngāti Pāoa, Ngāti Maru and Ngāti Whanaunga. Te Hīnaki and Te Horetā were thus warned that they were about to pay for the battle of Waiwhāriki.
When Hongi Hika led the massed Bay of Islands tribes against Mauinaina and Te Tōtara, the pā of Ngāti Pāoa and Ngāti Maru at present day Panmure and Thames, the local tribes, including Ngāti Whanaunga, withdrew into Waikato. No record remains of Te Horetā's role in these two major battles. It is known that he was in Waikato for the marriage of Te Wherowhero to Ngāwaero, probably in late 1821. It may have been in these wars that he earned the sobriquet Te Taniwha. On one occasion he dived from a high bank into a river, and, avoiding the spears of his foes, climbed from the water into the bow of an enemy canoe and drove off the defenders. Te Horetā's people, watching from the pā, thought the feat to be that of a taniwha.
Records are silent concerning Te Horetā's activities in the later 1820s. There is some evidence that at this time his people took refuge from marauding war parties at Haowhenua, on Little Barrier Island. From 1830 his principal residence appears to have been Kauaeranga. He was visited there by various missionaries. In January 1834, in his speech of welcome to William Yate, Te Horetā asked his people the rhetorical question: 'what have the missionaries come for'? His answer, as recorded by Yate, was that 'they have come to break our clubs and establish peace here'.
In the late 1830s Te Horetā was patron to William Webster, an American who established himself as a trader at Herekino Bay, Coromandel Harbour, with other stations at Waiomio and Kauaeranga. Webster, known as Wēpiha to local Māori, married a Ngāti Whanaunga woman. To the growing number of European timber workers and traders in the area the Ngāti Whanaunga leader was known as 'old Hooknose'. Te Horetā welcomed the visit of Major Thomas Bunbury in April–May 1840, and on 4 May 1840 signed the copy of the Treaty of Waitangi taken by Bunbury to Coromandel Harbour.
Probably in the mid 1840s Ngāti Whanaunga began gum-digging in the Colville area. While this provided an alternative economic activity for Te Horetā's people, it also renewed an old dispute between Ngāti Whanaunga and Ngāti Māhanga over land at Ahirau and Ōtautū. When Ngāti Whanaunga diggers established houses at Ōtautū, Te Waka of Te Uringahu and Ngāti Māhanga went there with a war party and set fire to them. Ngāti Whanaunga then pulled down a boundary marker of Te Waka, west of the Tauwhare range. Te Waka then went to Mekemeke and in an act of ritualised warfare fired his guns into the ground. After further acts of provocation on both sides peace initiatives were begun, with Te Horetā eventually agreeing to retain Ahirau, and Te Waka, Ōtautū and Tauwhare.
It was in Te Horetā's territories that gold was first discovered in New Zealand, in 1852, in the Kapanga River, near Coromandel Harbour. Intense interest followed the discovery, and a meeting was arranged by the government in November 1852 to negotiate access with the Māori owners of the land. Te Horetā and other influential Māori leaders met with the lieutenant governor of New Ulster, Colonel R. H. Wynyard, Bishop G. A. Selwyn and Chief Justice William Martin. By this time Te Horetā was 'bowed and enfeebled by age', being probably in his 90s. He willingly consented to his land being mined by the transient Pākehā, whom he compared to wandering albatross 'seeking food merely'.
Te Horetā Te Taniwha died at Coromandel Harbour on 21 November 1853. He had been baptised by the Anglican missionary Thomas Lanfear some four to six weeks before his death. Te Horetā had a second wife, Tuhi of Ngāti Naunau, and he was succeeded by their son, Kītahi Te Taniwha. On his deathbed he dictated a letter to a European friend in Auckland, asking him to guard the interests of both Europeans and Māori so that they could live together in peace.