Lake Suwa ( 諏訪湖 , Suwa-ko ) is a lake in the Kiso Mountains , in the central region of Nagano Prefecture , Japan .
6-566: The lake is the source of the Tenryū River . It ranks 24th in lake water surface area in Japan. The cities of Suwa and Okaya and the town of Shimosuwa are located on the shores of Lake Suwa. Lake Suwa is the site of a natural phenomenon known as the "God's Crossing" ( 御神渡り , o-miwatari ) , large cracks that form in the winter across the surface of the frozen lake. A vertical temperature gradient results in ice pressure ridges forming in
12-590: A result, it is expected that Lake Suwa will remain ice-free for almost the entirety of the 21st century's winters. Lake Suwa hosts two major shrines, the Tenaga Jinja and the Suwa Jinja. Major festivals include the Onbashira and Setsubun . Hokusai included Lake Suwa in his famous Thirty-six Views of Mount Fuji (Fugaku sanjūrokkei) series of woodblock prints . Epson , a global technology company,
18-418: Is the oldest-known human-observed climate record. This record has been used by scientists to study the impact of sunspots, human development and anthropogenic CO 2 emissions on lake ice formation. The lake has a natural hot spring under its surface. Recreational development in the 1950s resulted in increased output from this underwater geyser. Since 1945, complete ice cover is considered to be achieved when
24-532: The entire surface is frozen except for the opening in the ice for the geyser. As a shallow lake, Lake Suwa is highly sensitive to climatic variation. Recent studies have shown that Suwa's ice-free years correlate to increasing atmospheric CO 2 levels. Research on ice breakup at Suwa and at the mouth of the Torne River in Finland suggest that climate change is driving the changes in seasonal ice cover. As
30-526: The surface ice, reaching heights of 30 centimetres (1 ft) or more. Local Shinto tradition holds that the ridges are formed by the gods crossing the lake when traveling between the various buildings of the Suwa Grand Shrine . Folklore says it is the guardian god of Suwa, Takeminakata-no-kami , leaving his sanctuary to meet with his wife, the goddess Yasakatome , joining the opposite bank by walking on frozen water. The record of this crossing
36-524: Was founded and is headquartered in Suwa. In 2020, in advance of the scheduled Tokyo 2020 Summer Olympics , a new rowing boathouse and training facility was established in Shimosuwa. In the movie Kagemusha by Akira Kurosawa , the corpse of Lord Shingen is dropped into the lake. This film dramatizes the events leading up to the 1575 Battle of Nagashino . Sayo Masuda , author of Autobiography of
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