From, a patch of the Coral Sea, where Sandy Island doesn’t exist

I’m still following Boston events closely, but for a mental break from all that, let’s talk about Sandy Island — the island that never was but always will be, thanks to the magic of digital information that is easily reproduced even when it’s wrong (pardon the run-on sentence — due to the sequester I’m short on periods).

I wrote about Sandy Island in Monday’s paper. The island was purportedly discovered in 1876 by the whaling ship Velocity. It popped up on maps soon thereafter.

There is no island there. An Australian expedition last fall sailed to that part of the Coral Sea and, although they saw Sandy Island on their scientific data set, they found only open ocean, with nearly mile-deep water.

This is a story about how hard it is to correct an error. Cartographers copy each other (I’m told that some mapmakers invent “paper towns,” utterly fictitious, as a way of catching someone who illegally copies their work). Sandy Island was repeatedly “undiscovered,” and scrubbed from subsequent maps, but it somehow survived here and there. I saw it on a U.S. Defense Mapping Agency map dated 1982. I was assured by the National Geospatial Intelligence Agency (the successor to the DMA) that Sandy Island hasn’t been on a military map for years. But here’s the problem: Sandy Island was on the paper charts when they were converted to digital formats years ago. Those digital databases were used in various derived databases that are still around and which still show Sandy Island. And thus even though this Sandy Island error was publicized last fall, and even though the cartographers of the world — including the people at Google Earth and National Geographic — have removed it from their maps, the island is still around on certain derived databases. For example, we found it in the database used at The Post. Once an error is made, it is hard to track it down everywhere it might have wandered.

I found Sandy Island this morning on a database run by the National Geophysical Data Center, part of NOAA. Take a look. There’s a link to Online Coastline Extractor. Sandy Island is seen right along 160 degree E. longitude line, west of New Caledonia (it would be hard to find if you didn’t know where it was). But there’s also a prominent warning directly below the link, on the home page, to the Online Coastline Extractor: “Coastlines available through the online extractor are not updated, not authoritative, and most are deprecated.” The warning suggests using a different database that is updated and maintained. And then when you link to the Extractor, you get a glowing-red warning: Caution: These data are outdated. So, fair warnings. Still, I wonder why someone can’t go into the outdated data base and try to erase the island. Like, now.

From a reader at the State Department comes this email: “Seems like an arcane topic (fictitious island) until one views it as a ‘tip of the iceberg’ issue regarding old legacy cartographic data being repackaged and redistributed these days with a seemingly fresh, up to date imprimatur and flashy display, even though it’s often the ‘same old data.'”

And I think it goes beyond cartographic data: the Web is full of information that isn’t true. It’s easily reproduced with cut-and-paste technology. I guess you could point out that we all have books in our basements that are filled with bad information as well (paging Erich Von Daniken!). But I think the Web is particularly good at putting an authoritative gloss on squishy information.

Here’s the lede of my Sandy Island story:

A research ship cruised through the Coral Sea, east of Australia, bearing down on Sandy Island. The digital scientific databases used by the researchers showed the island to be 15 miles long, north to south, and about three miles wide. Manhattan-sized.

But when the ship reached the place where the island should have been, the researchers saw only open ocean. The water was nearly a mile deep. Sandy Island simply wasn’t there. Or, it turned out, anywhere.

How could an island supposedly discovered in 1876, and appearing on many maps ever since, vanish? Did it sink beneath the waves like the mythical Atlantis? Or was it always a figment of some mariner’s imagination?

The bizarre and complicated story of ghostly Sandy Island is a cautionary tale about what we know and don’t know in the 21st century — and how, even with satellite technology and modern surveying instruments, the ocean can still spring a surprise.

Last October, Maria Seton, a young scientist at the University of Sydney, led a 25-day expedition to the Coral Sea aboard the Australian national research vessel RV Southern Surveyor. The researchers wanted to understand the tectonic evolution of that corner of the Pacific. They gathered magnetic and gravity data to map the sea floor and collected rock samples from the bottom at depths up to two miles.

They noticed that multiple scientific data sets, including the General Bathymetric Chart of the Oceans, showed Sandy Island clearly in a remote area west of New Caledonia. But the chart used by the ship’s master indicated only open water. Seton and her fellow sailors realized something didn’t add up.

“We had a cached version of Google Earth for the area — we had no Internet — and saw that the ‘island’ was depicted as a big black blob. This also made us very suspicious,” she said.

Seton’s “undiscovery” of the island prompted a story in the Sydney Morning Herald that went viral. This was big news in the world of cartography; experts were puzzled, and some wondered if Sandy Island had been eroded away by the waves, like some ephemeral coral atolls. Google and National Geographic quickly removed Sandy Island from all of their maps.

Seton, meanwhile, dug into the mystery and has now published an obituary of Sandy Island in EOS, the journal of the American Geophysical Union.

Her research showed that the island appeared on the 1908 edition of a British admiralty map, which indicated that Sandy Island had been discovered in 1876 in French territorial waters by the whaling ship Velocity. The location and shape of the island on the 1908 map corresponds to what can be seen in the modern, erroneous databases.

The island was repeatedly “undiscovered” over ensuing decades, but it remained a shadowy presence in the cartographic world. Some maps labeled it “ED,” for “existence doubtful.” French hydrographic maps deleted Sandy Island once and for all in 1974.

But the island kept popping up in other places. The island was clearly marked, for example, on a 1982 U.S. Defense Mapping Agency map. “Ile de Sable,” it says, giving the French name. There’s a cryptic annotation: “Reported 1876. Reported to be about 4 miles east, 1968.”

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