Lake Baikal is the world's deepest and oldest freshwater lake, located in Siberia, Russia. It reaches a maximum depth of about 1,642 meters (5,387 feet) and is estimated to be around 25 million years old. The lake holds approximately 20% of the world's unfrozen freshwater, making it a vital natural resource. The unique ecosystem of Lake Baikal is home to thousands of plant and animal species, many of which are found nowhere else on Earth. Notable inhabitants include the Baikal seal, the only freshwater seal species, and various endemic fish species, contributing to the lake's rich biodiversity.