Blue Lake (Croatian: Modro jezero or Plavo jezero) is a karst lake located near Imotski in southern Croatia. Like the nearby Red Lake, it lies in a deep sinkhole possibly formed by the collapse of an enormous cave. The total depth from the upper rim is around 220 metres (720 ft), while water depth varies with season. In spring, when the snow from surrounding mountains melts, it can reach 90 m (300 ft), and in 1914 it reached 114 m (374 ft), overflowing the southern rim. The lake is a popular destination for hiking and sight-seeing.