Hirokawara
The longer of the two walking paths through Kikuchi Gorge turns back toward the visitor center at Hirokawara, a wide section of the river where the water is shallow and flows relatively slowly. Here the path snakes between pools inhabited by frogs, small salamanders, and water insects. It also passes over rocky ground broken into a conspicuous grid pattern. The rock is some 270,000 years old, formed from volcanic ash unleashed by an eruption of nearby Mt. Aso. The grid pattern was formed when the welded rock cooled and cracked, and the cracks slowly deepen as water flows over them.
Yamame (landlocked masu salmon), one of the only two species of fish living in Kikuchi Gorge, can sometimes be seen in the pools under the bridge at Hirokawara. Also occasionally visible from the bridge, particularly in the upstream direction, are green tufts of kawanori, a type of edible algae that grows in rivers. Kawanori has been part of the local diet since antiquity, and algae harvested from Kikuchi Gorge was once considered a delicacy. The daimyo lord of the Kumamoto domain would present local kawanori as a gift to the shogun during the Edo period (1603–1867). The plant is increasingly rare these days, and Kikuchi Gorge is one of the few places where it still grows.