Question: What animal is the largest member of the oceanic dolphin family and famously watched in New Zealand, particularly around the areas of Kaikoura and the Hauraki Gulf?

Context paragraphs:
Guiana dolphin: The Guiana dolphin ("Sotalia guianensis"), also known as the estuarine dolphin, is a dolphin found in the coastal waters to the north and east of South America, and east of Central America.  It is a member of the oceanic dolphin family (Delphinidae).  It can live both in saltwater and in freshwater.

Hauraki Gulf: The Hauraki Gulf / Tīkapa Moana is a coastal feature of the North Island of New Zealand.  It has an area of 4000 km², and lies between, in anticlockwise order, the Auckland Region, the Hauraki Plains, the Coromandel Peninsula, and Great Barrier Island.  Most of the gulf is part of the Hauraki Gulf Marine Park.

Rangitoto Island: Rangitoto Island is a volcanic island in the Hauraki Gulf near Auckland, New Zealand.  The 5.5 km wide island is an iconic and widely visible landmark of Auckland with its distinctive symmetrical shield volcano cone rising 260 metres (850 ft) high over the Hauraki Gulf.  Rangitoto is the most recent and the largest (2311 hectares) of the approximately 50 volcanoes of the Auckland volcanic field.  It is separated from the mainland of Auckland's North Shore by the Rangitoto Channel.  Since World War II it has been linked by a causeway to the much older, non-volcanic Motutapu Island.

Melon-headed whale: The melon-headed whale or melon-headed dolphin (species "Peponocephala electra"; other names are many-toothed blackfish, "melon whale" and electra dolphin) is a cetacean of the oceanic dolphin family (Delphinidae).  Theorized in the 1970s, it is closely related to the pygmy killer whale and pilot whale, and collectively these dolphin species are known by the common name blackfish.  It is also related to the false killer whale.  The melon-headed whale is widespread throughout the world's tropical waters, although not often seen by humans because it prefers deep water.

Coromandel Peninsula: The Coromandel Peninsula on the North Island of New Zealand extends 85 kilometres north from the western end of the Bay of Plenty, forming a natural barrier to protect the Hauraki Gulf and the Firth of Thames in the west from the Pacific Ocean to the east.  It is 40 kilometres wide at its broadest point.  Almost the entire population lies on the narrow coastal strips fronting the Hauraki Gulf and the Bay of Plenty.  In fine weather the peninsula is clearly visible from Auckland, the country's biggest city, which lies on the far shore of the Hauraki Gulf, 55 kilometres to the west.  The peninsula is part of the local government areas of Thames-Coromandel District and the Waikato Region.

Motutapu Island: Motutapu Island (or simply "Motutapu") is a 1509 ha island in the Hauraki Gulf to the northeast of the city of Auckland, New Zealand.  The island is part of the Hauraki Gulf Maritime Park.

Killer whale: The killer whale or orca ("Orcinus orca") is a toothed whale belonging to the oceanic dolphin family, of which it is the largest member.  Killer whales have a diverse diet, although individual populations often specialize in particular types of prey.  Some feed exclusively on fish, while others hunt marine mammals such as seals and dolphins.  They have been known to attack baleen whale calves, and even adult whales.  Killer whales are apex predators, as there is no animal that preys on them.  Killer whales are considered a cosmopolitan species, and can be found in each of the world's oceans in a variety of marine environments, from Arctic and Antarctic regions to tropical seas.

North Head, New Zealand: Maungauika is a volcano forming a headland called North Head at the east end of the Waitemata Harbour in Auckland, New Zealand in the suburb of Devonport.  Known for its sweeping views over the harbour and the Hauraki Gulf, since 1885 the head was mainly used by the military as a coastal defence installation, which left a network of accessible old bunkers and tunnels as its legacy, forming part of the attraction.  The site was protected as part of Hauraki Gulf Maritime Park in 1972 and listed as a Category I historic place in 2001.  As part of a 2014 Treaty of Waitangi claim settlement the volcanic cone was officially named Maungauika and the reserve renamed Maungauika / North Head Historic Reserve.  Maungauika is the Māori word for" Mountain of Uika".

Whale watching in New Zealand: Whale watching in New Zealand is predominantly centered around the areas of Kaikoura and the Hauraki Gulf.  Known as the 'whale capital', Kaikoura is a world-famous whale watching site, in particular for sperm whales which is currently the most abundant of large whales in New Zealand waters.  The Hauraki Gulf Marine Park (just outside Auckland city) is also a significant whale watching area with a resident population of Bryde's Whales commonly viewed alongside other cetaceans Common Dolphins, Bottlenose Dolphins and Orca.  Whale watching is also offered in other locations, often as eco-tours and in conjunction with dolphin watching.  Land-based whale watching from New Zealand's last whaling station, which closed in 1964, is undertaken for scientific purposes, mostly by ex-whalers.  Some compilations of sighting footages are available on YouTube.

Kaikoura Island: Kaikoura Island (formerly known as Selwyn Island) lies in an irregularly-shaped bay on the western side of Great Barrier Island in the Hauraki Gulf in New Zealand, 90 km north east of Auckland.  Kaikoura Island is the seventh largest island in the Hauraki Gulf.  It is 80 metres from Great Barrier Island at its closest point and forms the natural harbours of Port FitzRoy and Port Abercrombie.  Its biota includes the endangered brown teal duck, the North Island kaka and many native trees and shrubs.

Supporting paragraphs: Whale watching in New Zealand Killer whale
Answer: Killer whales