Jellyfish Lake, Eil Malk Island, Palau, Pacific Ocean

The stratification of the lake is caused by conditions which prevent or restrict the mixing of water vertically. These conditions include:
1. The lake is surrounded by rock walls and trees which substantially block the wind flow across the lake that would cause mixing.
2. The primary water sources for the lake (rain, runoff and tidal flows through tunnels) are all close to the surface.
3. The lake is in the tropics where seasonal temperature variation is small so that the temperature inversion that can cause vertical mixing of lakes in temperate zones does not occur.