This article lists lakes with a water volume of more than 100 km3, ranked by volume. The volume of a lake is a difficult quantity to measure.[1] Generally, the volume must be inferred from bathymetric data by integration. Lake volumes can also change dramatically over time and during the year, especially for salt lakes in arid climates. For these reasons, and because of changing research, information on lake volumes can vary considerably from source to source. The base data for this article are from The Water Encyclopedia (1990).[2] Where volume data from more recent surveys or other authoritative sources have been used, that usage is referenced in the respective entry. The total volume of Earth's lakes is 199,000 km3.[1]