阿寒湖[ Akan ko ]Lake Akan
Lake Akan (阿寒湖, Akan-ko) is a lake in Kushiro, Hokkaidō, Japan. It is located in Akan National Park and is a Ramsar Site. Volcanic activity formed the lake some 6,000 years ago, when a dam was formed. The lake used to have a clarity of 8–9 meters in the 1930s. Pollution from local hotspring resorts has decreased the transparency to 3–4 meters.