In Māori mythology, Hawaiki is the homeland of the Māori, the original home of the Māori, before they travelled across the sea to New Zealand. It also features as the underworld in many Māori stories.

Linguists have reconstructed the term to Proto-Nuclear Polynesian *sawaiki.

The Māori word Hawaiki figures in legends about the arrival of the Māori in Aotearoa (New Zealand). The same concept appears in other Polynesian cultures, the name appearing variously as Havaiki, Havai'i, or 'Avaiki in other Polynesian languages, though Hawaiki or the misspelling "Hawaiiki" appear to have become the most common variants used in English. Even though the Sāmoans have preserved no traditions of having originated elsewhere, the name of the largest Sāmoan island Savaiʻi preserves a cognate with the word Hawaiki, as does the name of the Polynesian islands of Hawaiʻi (the ʻokina denoting a glottal stop that replaces the "k" in some Polynesian languages).

In several island groups including New Zealand and the Marquesas the term has been recorded as associated with the underworld and death.William Wyatt Gill discusses at length the legends about 'Avaiki as the underworld or Hades of Mangaia in the Cook Islands. Gill (1876:155) records a proverb: Ua po Avaiki, ua ao nunga nei – 'Tis night now in spirit-land, for 'tis light in this upper world." Tregear (1891:392) also records the term Avaiki as meaning "underworld" at Mangaia, probably sourced from Gill. There is of course no real contradiction in Hawaiki being the ancestral homeland (that is, the dwelling place of the ancestors) and the underworld, which is also the dwelling place of the ancestors and the spirits.