Lake Towada

Lake Towada is the largest crater lake in Honshū island, Japan. Located on the border between Aomori and Akita prefectures, it lies 400 meters above sea level and is 327 m deep, drained by the Oirase river. With a surface area of 61.1 km², Towada is Japan's 12th largest lake, its bright blue color is due to its great depth. The lake is roughly circular, with two peninsulas extending from its southern shore approximately one-third into the center of the lake. The lake is a popular tourist destination.

Source: Wikipedia