With a surface area of 61.1 km2 (23.6 sq mi), Towada is Japan's 12th largest lake; its bright blue color is due to its great depth.
It forms part of the northern section of Towada-Hachimantai National Park[1] Lake Towada occupies the caldera of a stratovolcano still regarded as active.
According to the National Institute for Environmental Studies of Japan, the water renewal cycle of Lake Towada is approximately 8.5 years.
[4][5] According to a legendary account, the Yamata general Sakanoue Tamuramaro visited Lake Towada during one of his expeditions north to conquer the Emishi tribes and built a small Shinto shrine on the eastern shore of the Nakayama peninsula in 807 AD dedicated to Yamato Takeru.
[6][7] The mountain continued to erupt well into the historical period, with the last recorded eruption occurring in 915 AD in the Nakaumi caldera, devastating the surrounding area with pyroclastic flows and lahars and covering most of the Tōhoku region of Japan with volcanic ash, leading to crop failures, climate change, and famines.
During the Heian and Kamakura Period, the area was a wilderness and a place of prayer and training for Yamabushi,[8] including worship of Suijin, the kami of water, as being associated with the azure dragon, legendary guardian of the lake, hence the other name of the sanctuary: Towadasan Seiryū daigongen.
A wartime Tachikawa Ki-54 aircraft of the Imperial Japanese Army Air Force which crashed in 1943 was found at the bottom of Lake Towada on 13 August 2010.