The Shimanto River (Shimantogawa) is a river in western Kochi Prefecture. It is 196 kilometers in length. Since the river is remote from major cities and has no big dams, it is sometimes referred to as 'the last clear stream of Japan'. Fishing and production of nori is a thriving industry along the river. The Shimanto River has been named one of the 'Three Clear-Flowing Rivers in Japan', along with the Nagara River in Gifu Prefecture and the Kakita River in Shizuoka Prefecture. It also has 47 'chinkabashi' (sinking bridges) including those of tributaries. Chinkabashi are bridges without parapets in order not to be washed away by floods. The prefecture decided to preserve them as cultural heritage.