is the biggest crater lake on honshū island, japan. it is on the border between aomori and akita prefectures. it is 400 meters (1,800 ft) above sea level, and it is 327 m (1,073 ft) deep. the oirase river drains it. it has a surface area of 61.1 km². this makes it japan's 12th biggest lake. it has a bright blue color because it's very deep. the lake is shaped like a circle. it has two peninsulas starting on its southern shore about one-third into the center of the lake.