Tuanaki or Tuanahe is the name of an anecdotal vanished group of islets, once part of the Cook Islands. It was located south of Rarotonga^[1] and within two days sail of Mangaia.^[2]

In 1916, the Polynesian Society of Honolulu reprinted an account by a sailor who had visited there in 1842, spending six days among the natives. However this account added that two years later in 1844, a schooner of English missionaries had found nothing.^[3] Some Tuanakians who had emigrated to Rarotonga allegedly survived.

The 1916 publication re-ignited interest in the flyaway islands, and explorer Sir Ernest Shackleton, when planning the Shackleton-Rowett Expedition of 1921–1922, proclaimed as one of his goals the rediscovery of Tuanaki. The explorer died in Antarctic waters before he was able to mount a serious search for the vanished archipelago.^[4]

It was suggested in 1952 that the Haymet Rocks were a remnant of Tuanaki.^[5] However, the existence of the Haymet Rocks at some point is unconfirmed as well.