Last month, a group of Australian scientists studying plate tectonics in the Coral Sea noticed that a small, uninhabited Pacific island appeared on some of their charts, but not on others. Labeled Sandy Island (or sometimes Île de Sable), this tiny islet had been presumed to lie within French territorial waters for centuries. So the scientists aboard the Southern Surveyor plotted a course for Sandy Island. They arrived at the “island” to find nothing but open sea, with the ocean floor almost a mile deep at its shallowest point. So where did Sandy Island go?

View Sandy Island in a larger map

In the following week, geographers quickly determined that Sandy Island hadn’t disappeared: It had never really existed in the first place. In 1876, a whaling ship called the Velocity drew some dotted lines on the map at this point, noting “heavy breakers” and “sandy islets” in the ship’s log. What did they see? There’s no way to be sure. It could have been part of a reef, or maybe they were off-course. But their dotted “Sandy Island” was later noticed and enshrined by mapmakers, who probably conflated it with another Sandy Island that Captain Cook had noted about 260 miles to the east. The error kept getting propagated on new maps for well over a century, and the island is far enough from established shipping lanes that no one ever noticed it was gone.

This isn’t the first time a map mistake like this has been propagated down through the centuries. An African mountain range with a name straight out of a Tarzan movie, the Mountains of Kong, appeared on British maps in 1798, based on scattered reports that had reached surveyor James Rennell. Remarkably, the label stuck around in atlases until 1928, even though the mountains didn’t exist.

Until 1910, the International Date Line took a little jog to avoid Morrell Island, another dot of land that never was. Captain Benjamin Morrell, its “discoverer,” described lots of hard-to-believe adventures on the seven seas and was called “the biggest liar in the Pacific” by other explorers of his day. In 1875, an exasperated British naval captain named Frederick Evans got tired of all the phantom Pacific islands and erased more than 120 of them from the Crown’s nautical charts.