The largest lake in the Arctic region is Lake Baikal, located in Siberia, Russia. Contrary to being in the Arctic Circle, it significantly impacts the region's ecosystem and climate. It is known for its amazing depth and is considered the oldest freshwater lake in the world, holding about 20% of the world's unfrozen freshwater. This unique lake features diverse biodiversity, including a variety of endemic species, and is a UNESCO World Heritage Site. Its stunning beauty and ecological importance make it a significant geographical feature in the northern hemisphere.