Japanese geography textbooks are going to need a major update: The latest mapping survey has identified more than 7,000 previously unknown islands in the country’s waters. The finding more than doubles the number of Japanese islands, to 14,125, from the 6,852 found in the last survey, by the Japanese coast guard, in 1987. Since that last survey, Gizmodo explained, new geospatial technology has allowed mappers to distinguish small clusters of islands that were previously recorded as single masses. Repeated earthquakes over the past 35 years have also helped create new islands.