Quite near to the island of Mangaia was another island known as Tuanaki.Back in the early 1840s, this mystery island was shown on some maps of the South Pacific, and it was located about one day of sailing, south from Mangaia.
During World War 1, the Maunganui served as a troop ship; and during World War 2, it served as a hospital ship.
Did it really exist, or was it simply a matter of mis-identification of Mangaia itself, or of another island out there somewhere?
Geologists and historians consider that if the island did indeed exist a couple of hundred years ago, then it simply disappeared beneath the waters of the ocean in some unidentified cataclysmic event, maybe a seismic collapse with an underwater landslide.
However in 1924, this same callsign was then applied to a new wireless station that was installed onto the small island of Mangaia in the Cook Islands.
The island called Mangaia, the most southerly in the Cook Island archipelago in the South Pacific, was discovered by the English Captain James Cook in 1777.