The Ebro River delta in NE Spain has been changing over the past 60 years. By studying old and new maps, researchers found that one side of the river mouth is growing while the other is shrinking. The left side is getting bigger by 40 meters each year, but the right side is losing land at a rate of 20 meters per year. If this continues, the San Antonio Island may disappear by 2050. Urgent plans are needed to protect this important ecosystem.