The Kiso River is a major river in central Japan, flowing through the Kiso Valley in Nagano Prefecture and Gifu Prefecture. It is approximately 229 kilometers long and is known for its clear waters and scenic landscapes. The river is part of the Kiso Three Rivers, which also includes the Ibi River and Nagara River. The Kiso River has historical significance, as it was an important transportation route during the Edo period. It is also famous for its traditional wooden boats, known as kiso-bune, which were used for trade and travel. Today, the river is a popular destination for outdoor activities like fishing and hiking.