English: An astronaut aboard the International Space Station captured this photograph of part of Lake Van in Turkey, the largest soda or alkaline lake on Earth. Generally, soda lakes are distinguished by high concentrations of carbonate species. Lake Van is an endorheic lake—it has no outlet, so its water disappears by evaporation—with a pH of 10 and high salinity levels.

Waters near the city of Erciş (population 90,000) are shallow, but other parts of the lake can be up to 450 meters (1,467 feet) deep. Lake Van water levels have changed by 100s of meters over the past 600,000 years due to climate change, volcanic eruptions, and tectonic activity.

Turbidity plumes, which appear as swirls of light- and dark-toned water, are mostly comprised of calcium carbonate, detrital materials, and some organic matter. High particle fluxes occur in Lake Van during spring and fall, when phytoplankton and aquatic plants grow and produce a lot of organic carbon. The lake also hosts the largest known modern microbialite deposits.