Frank Jacobs writes at Big Think:
A phantom island can be defined as ‘An island once believed to exist, and accordingly depicted on maps, but of which the existence was later disproved, and its cartographic representation removed’. These fallacies started infesting maps by the dozen during the Age of Discovery, when explorers sailing for regions unknown mistook their fevered ambitions, or a random fog bank, for islands that weren’t there.
Some of these phantom islands lingered on maps for centuries, at least partly, it seems, because they had such a great hold on the imagination of generation after generation of sailors. But eventually, they were proven not to exist. Gone from today’s maps are places with such captivating names as the Isle of Demons, Estotiland, the Island of the 11,000 Virgins, and Hy-Brasil. All of these and more were un-discovered, removed from nautical charts, and added to the select club of Phantom Islands.
The most recent member of that club, as far as we could tell, was Sannikov Land. It was presumed to lie in the Arctic Sea off Siberia, ever since the Russian explorer Yakov Sannikov in 1811 reported a ‘bluish fog’ to the northeast of the New Siberian Islands. Distant mirages of the island were subsequently observed by the Baltic baron Edward Toll in 1886 and 1893, before their false promise lured him to his death in 1902, on a third expedition. Finally, the Soviet ice-breaker Sadko found only frozen sea where the island ought to be, relegating it to the Phantom Island Hall of Fame.
That was in 1937. And that seemed to be the very fag-end of the Age of Un-Discovery.
Cue to 21 November 2012, as the Australian RV (Research Vessel) Southern Surveyor puts into port at Brisbane, after a 25-day exploration of the tectonic framework for the easternmost Coral Sea, in the Pacific Ocean between the eastern coast of Australia and the French territory of Nouvelle Calédonie. The ship’s crew, marine geologists from the University of Sydney, have a strange tale to tell. During their expedition, they noticed that the sea floor beneath an island in the French part of the Coral Sea is recorded as 4,600 feet (1,400 m) deep. That seems odd. So they go and check it out.
Read more here.