For 100 years, maps have shown an island that doesn't exist:
Almost nothing is known about Sandy Island, a land mass about the size of Manhattan in the Pacific Ocean off the coast of Australia. Supposedly, explorer James Cook discovered it in 1774, and it began appearing on nautical maps in 1908. It wasn't until 2012, when a team of Australian scientists set out to survey the island, that they discovered there was no island there at all. The scientists guessed that Cook may have in fact spotted a "pumice raft" of floating volcanic stone and gas. The Sydney Morning Herald even published an obituary for Sandy Island.