Natural lakes are large bodies of freshwater or saltwater that form in depressions on the Earth's surface. They can be created through various geological processes, such as glacial activity, volcanic eruptions, or tectonic movements. These lakes are typically fed by rivers, streams, or rainfall and can vary greatly in size and depth. Natural lakes play a crucial role in the ecosystem, providing habitats for diverse wildlife and supporting plant life. They also serve important functions for humans, including recreational activities like fishing and boating, as well as being sources of drinking water. Examples of natural lakes include Lake Superior and Lake Baikal.