1. Jakarta, Indonesia
Jakarta is sinking faster than almost any other city on Earth — up to 6.7 inches each year. This happens because too much groundwater is taken from underground. If it continues, large parts of the city could be underwater by 2050, putting over 10 million people at risk.
To keep people safe, Indonesia plans to move its capital 100 miles away to Borneo. The move will cost $33 billion and take about ten years, showing how serious the problem is for many coastal cities.