The country that has the largest lake in the world is Russia, which is home to Lake Baikal. This ancient lake is not only the deepest freshwater lake but also the most voluminous, containing around 20% of the world's unfrozen surface freshwater. Lake Baikal is renowned for its unique biodiversity, including species found nowhere else, such as the Baikal seal. It is recognized as a UNESCO World Heritage site, reflecting its ecological importance and cultural significance to the surrounding communities.