Just like the mountains, lakes on Earth can be ancient, or more than 1 million years old. There are only 20 ancient lakes on the planet, but which is the oldest?
Earth's oldest lake has a clear winner: Lake Baikal in southeast Siberia. Scientists estimate that this enormous freshwater body is 25 million years old, according to Ted Ozersky, an associate professor of biological limnology (the study of inland bodies of water) at the University of Minnesota. By contrast, the Great Lakes formed less than 20,000 years ago. The second oldest lake on Earth is Lake Issyk-Kul in Kyrgyzstan, which formed about 20 million years ago.
