Inlet hole to Jellyfish Lake, in Palau. This lake is one of only a handful of stratified saltwater lakes in the world. It is connected to the sea through three holes near the surface, which allow salt water to flow in and out, with an approximately 100_minute delay from the tidal flow. This process exchanges around 2.5 of the lake磗 volume with each tide. The lake remains stratified because the holes are near the surface. Its isolation from the ocean has allowed a unique ecosystem to develop. The upper layers are teeming with a unique species of jellyfish Mastigias cf. papua etpisoni, while the deeper layer is anoxic, acidic and devoid of life.