Taniwha

In Māori mythology, taniwha (Māori pronunciation: [ˈtanifa]) are beings that live in deep pools in rivers, dark caves, or in the sea, especially in places with dangerous currents or deceptive breakers (giant waves). They may be considered highly respected kaitiaki (protective guardians) of people and places, or in some traditions as dangerous, predatory beings, which for example would kidnap women to have as wives.

Linguists have reconstructed the word taniwha to Proto-Oceanic *tanifa, with the meaning "shark species". In Tongan and Niuean, tenifa refers to a large dangerous shark, as does the Samoan tanifa; the Tokelauan tanifa is a sea-monster that eats people. In most other Polynesian languages, the cognate words refer to sharks or simply fish. Some anthropologists have stated that the taniwha has "analogues that appear within other Polynesian cosmologies".

At sea, a taniwha often appears as a whale or as quite a large shark; compare the Māori name for the Great white shark: mangō-taniwha. In inland waters, they may still be of whale-like dimensions, but look more like a gecko or a tuatara, having a row of spines along the back. Other taniwha appear in forms of serpentine, dragon-like (both in eastern and western lores), crocodile-like, and megalania - like, or as a floating log, which behaves in a disconcerting way (Orbell 1998:149-150, Reed 1963:297). Some can tunnel through the earth, uprooting trees in the process. Legends credit certain taniwha with creating harbours by carving out a channel to the ocean. Wellington's harbour, Te Whanganui-a-Tara, was reputedly carved out by two taniwha. The petrified remains of one of them turned into a hill overlooking the city. Other taniwha allegedly caused landslides beside lakes or rivers.

...
Wikipedia