A South Pacific island, shown on marine charts and world maps as well as on Google Earth and Google Maps, does not exist, Australian scientists say.
The supposedly sizeable strip of land, named Sandy Island on Google maps, was positioned midway between Australia and French-governed New Caledonia.
But when scientists from the University of Sydney went to the area, they found only the blue ocean of the Coral Sea.
The phantom island has featured in publications for at least a decade.
Scientist Maria Seton, who was on the ship, said that the team was expecting land, not 1,400m (4,620ft) of deep ocean.
"We wanted to check it out because the navigation charts on board the ship showed a water depth of 1,400m in that area - very deep," Dr Seton, from the University of Sydney, told the AFP news agency after the 25-day voyage.
"It's on Google Earth and other maps so we went to check and there was no island. We're really puzzled. It's quite bizarre.
"How did it find its way onto the maps? We just don't know, but we plan to follow up and find out."
Australian newspapers have reported that the invisible island would sit within French territorial waters if it existed - but does not feature on French government maps.
Australia's Hydrographic Service, which produces the country's nautical charts, says its appearance on some scientific maps and Google Earth could just be the result of human error, repeated down the years.
A spokesman from the service told Australian newspapers that while some map makers intentionally include phantom streets to prevent copyright infringements, that was was not usually the case with nautical charts because it would reduce confidence in them.
A spokesman for Google said they consult a variety of authoritative sources when making their maps.
"The world is a constantly changing place, the Google spokesman told AFP, "and keeping on top of these changes is a never-ending endeavour'.'
The BBC's Duncan Kennedy in Sydney says that while most explorers dream of discovering uncharted territory, the Australian team appears to have done the opposite - and cartographers everywhere are now rushing to undiscover Sandy Island for ever.