Shimanto Sink Bridges — Drive Over, Not Under

The Shimanto River is crossed by 47 chinkabashi — low-slung, railing-free concrete bridges designed to be submerged during floods. The name means 'sink bridge,' and the design philosophy is simple: rather than build tall, expensive bridges that might be destroyed by typhoon-driven floods, build low, simple spans that let water pass over them. When the river rises, the bridges disappear underwater for days; when it recedes, they emerge unscathed.

Driving or cycling across a chinkabashi is a unique experience — the road surface is barely a meter above the river, there are no railings, and the sensation is of driving on the water itself. The most famous and photogenic is Iwama Chinkabashi, a 120-meter span with views upstream to forested hills and downstream to rice paddies. Other notable bridges include Sada Chinkabashi (291 meters, the longest) and Katsuma Chinkabashi (the lowest and most flood-prone).