Lake Suwa, the perimeter of 17 kilometers, height above sea level of 760 meters and average depth of 4.7 meters, lies in Suwa Basin in Nagano Prefecture. It used to thickly freeze over the entire surface every winter, so that a military drill such as tank driving training and fighter taking off and landing training were carried out making the most of the thick ice. Repeated freezing over suddenly causes pressure ridges on the surface of the thick ice with a loud noise, which is called Omiwatari in this neighborhood. The locals thought these ice ridges must be the traces of a god and goddess of the shrine both sides of the lake. Two gods met each other in the middle of the lake on foot. This Omiwatari ritual dates back to the 12th century according to the old documents. However, the chance of their dating is dropping recently due to global warming. Licensed tour guide, travel consultant, Masahisa Takaki.