is a

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much lar ...

in the Kiso Mountains, in the central region of

Nagano Prefecture is a landlocked prefecture of Japan located in the Chūbu region of Honshū. Nagano Prefecture has a population of 2,052,493 () and has a geographic area of . Nagano Prefecture borders Niigata Prefecture to the north, Gunma Prefecture to the n ...

, Japan.

Geography

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.

Omiwatari

Lake Suwa is the site of a natural phenomenon known as the , 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 the surface ice, reaching heights of or more. 180205 Lake Suwa omiwatari 01

Local

Shinto Shinto () is a religion from Japan. Classified as an East Asian religion by scholars of religion, its practitioners often regard it as Japan's indigenous religion and as a nature religion. Scholars sometimes call its practitioners ''Shintoist ...

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 , joining the opposite bank by walking on frozen water. The record of this crossing 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 CO₂ emissions on lake ice formation. The lake has a natural

hot spring A hot spring, hydrothermal spring, or geothermal spring is a spring produced by the emergence of geothermally heated groundwater onto the surface of the Earth. The groundwater is heated either by shallow bodies of magma (molten rock) or by c ...

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 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 CO₂ levels. Research on ice breakup at Suwa and at the mouth of the Torne River in

Finland Finland ( fi, Suomi ; sv, Finland ), officially the Republic of Finland (; ), is a Nordic country in Northern Europe. It shares land borders with Sweden to the northwest, Norway to the north, and Russia to the east, with the Gulf of Bo ...

suggest that climate change is driving the changes in seasonal ice cover. As a result, it is expected that Lake Suwa will remain ice-free for almost the entirety of the 21st century's winters.

Cultural history

Lake Suwa hosts two major shrines, the Tenaga Jinja and the Suwa Jinja. Major festivals include the

Onbashira The are four wooden posts or pillars that stand on the four corners of local shrines in the Lake Suwa area of Nagano Prefecture (historical Shinano Province), Japan. The largest and most famous set of are those that stand on the four shrines ...

and Setsubun. Lake Suwa in the Shinano province

Hokusai included Lake Suwa in his famous Thirty-six Views of Mount Fuji (Fugaku sanjūrokkei) series of woodblock prints. Epson, a global technology company, was founded and is headquartered in Suwa.

In popular culture

In the movie '' Kagemusha'' by

Akira Kurosawa was a Japanese filmmaker and painter who directed thirty films in a career spanning over five decades. He is widely regarded as one of the most important and influential filmmakers in the history of cinema. Kurosawa displayed a bold, dy ...

, the corpse of Lord Shingen is dropped into the lake. This film dramatizes the events leading up to the 1575

Battle of Nagashino The took place in 1575 near Nagashino Castle on the plain of Shitaragahara in the Mikawa Province of Japan. Takeda Katsuyori attacked the castle when Okudaira Sadamasa rejoined the Tokugawa, and when his original plot with Oga Yashiro for t ...

. Sayo Masuda, author of '' Autobiography of a Geisha'', was sold by her family to an

okiya An is the lodging house/drinking establishment to which a or geisha is affiliated with during her career as a geisha. The is typically run by the "mother" () of the house, who handles a geisha's engagements, the development of her skills, and ...

(geisha house) in Suwa at the age of 12. She tries to drown herself in the lake, but hesitates because she believes a dragon (possibly related to the omiwatari) inhabits it. *In the anime '' Rurouni Kenshin'', legend holds of an "Elixir of Immortality" that can be found somewhere in or around Lake Suwa. The main characters search for the elixir in the final season of the series and are followed by a band of evil German knights, seeking it for world domination. *The anime '' Blood-C'' takes place in a rural town located on the shore of the lake. *Suwako Moriya from the ''

Touhou Project The , also known simply as , is a bullet hell shoot 'em up video game series created by one-man independent Japanese ''doujin'' soft developer Team Shanghai Alice. Since 1995, the team's member, Jun'ya "ZUN" Ōta, has independently develope ...

'' is named after the lake. *This lake is also popular because from the movie of '' Your Name'' as it gained its tourist visitors. The Itomori town where Mitsuha (Main Female Protagonist) lived was modeled after the Lake Suwa in Gifu.

References

{{Authority control Suwa Landforms of Nagano Prefecture Kiso Mountains

Geography

Omiwatari

Cultural history

In popular culture

See also

References