Shimanto River

The Shimanto River seen from a place near Nakamura

The Shimanto River (四万十川 Shimantogawa) is a river in western Kochi Prefecture, Japan. 196 km in length, it has a watershed of 2,270 km².

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 river also has 47 chinkabashi (沈下橋 lit. 'sinking bridge') including those of tributaries. Chinkabashi are bridges without parapets in order not to be washed away by floods. The prefecuture decided to preserve them as cultural heritages.