In Polynesian mythology, Avaiki is an underworld, ruled by Miru and built by the gods in a series of caves and tunnels, leading to multiple halls. The lowest of the halls is the abode of Varima-te-Takere. Alternatively, Rongo created Avaiki beneath the island of Mangaia (Cook Islands). As another possibility, Avaiki is the name of the oven wherein Miru burns dead souls for eternity.

In addition to Miru and Varima-te-Takere, Miru's daughters, the Tapairu, live in Avaiki.

Some Polynesians believe Avaiki is their ancestral homeland.