A mysterious island dubbed Sandy Island that appeared on maps of the area around northwest Caledonia was officially "undiscovered" by researchers.
It even popped up on Google Earth leading researchers to search for it in 2012. However, they did not find any land mass at the given coordinates. Per reports, it just happened to be a nonexistent landmass that was accidentally included in maps: "In an obituary for the island published in April 2013, the researchers explained why the phantom landmass had been included on some maps for more than a century, pointing to some human errors and a possible pumice raft."
First discovered by the whaling ship Velocity in 1876, Sandy Island remained elusive to other expeditions and was subsequently removed from hydrographic charts by the 1970s. Why the crew of the Velocity mistook it for an island continued to baffle researchers until some speculated that the reason could very well be a giant pumice raft.
Pumice is a frothy, light rock produced in volcanic eruptions. Huge mats of pumice can float on the ocean before eventually breaking to pieces as this excerpt explains: "Pumice forms when volcanic lava cools quickly, trapping gas inside and creating lightweight rocks that can float. Last summer, an erupting undersea volcano called the Havre Seamount sent pumice drifting off the coast of New Zealand across an astounding area of 8,500 square miles (22,000 square kilometers). And Sandy Island happens to sit along a pumice "superhighway."