In 1858, a ship crew representing the New York Guano company — yes, there once was such an enterprise — was out searching in the Pacific for promising sources of bird poop fertilizer. They discovered a tiny island, which they named Sarah Anne and claimed for the company. They marked it down as latitude 4 north, longitude 154.22 west. Mariner's charts put it slightly to the northeast of Christmas Island,
Fifteen years later, the USS Portsmouth tried without success to find Sarah Anne Island at those coordinates. The U.S. government's official mapmakers, though, refused to concede that it didn't exist.
None of that really mattered much until 1937, when astronomers started preparing to observe an eclipse. The event would only last for seven minutes, and the scientists figured out that the only dry land in the Pacific that gave them a suitable vantage point during that time was Sarah Anne Island.
So the government mapmakers scrutinized the chart again. Their conclusion was that someone had written down the coordinates slightly wrong — it should have been latitude 4 south, which matched the coordinates for Independence Island (or Malden Island), another land mass that was near Christmas Island. So Sarah Anne became the only island ever to vanish due to clerical error [source: Associated Press].