Lake Batalon, Hungary [huanqiu.com]

9. Lake Balaton of Hungary, often affectionately called the "Hungarian Sea," is the largest lake in Central Europe, and one of Hungary's foremost tourist destinations. It lies among the volcanic hills in the western Hungary and stretches nearly 77 kms. But in recent years, the rising temperature and the reduction of rainfall has already caused the shrinkage of the lake. If this tendency went on, most of the lake area would finally dry up.