Hundreds of islands that once appeared on nautical charts and general atlases are now known to have vanished — or never even existed. How were they detected in the first place? Henry Stommel, an oceanographer and senior scientist at Massachusetts' Woods Hole Oceanographic Institute, chronicles his fascinating research in documenting the false discoveries of these phantom islands. British and American Hydrographic Offices compiled lists for navigators of reported dangers corresponding to the islands' supposed locations, which formed the basis for Stommel's surveys. These tales, which unfold according to location, blend historical and geographic background with intriguing anecdotal material. They relate how the small land formations came to be charted, who reported them, who eradicated them, and why some of them endured for so long. The chronicle of navigational errors, optical illusions, wishful thinking, and other mishaps is illustrated by scores of black-and-white images, including two 19th-century Admiralty charts of the Indian and Pacific Oceans, where most of the sightings took place.