The source of the Tone River is at Mount Ōminakami [Wikidata] (大水上山) (1,831 meters (6,007 ft)) in the Echigo Mountains, which straddle the border between Gunma and Niigata Prefectures in Jōshin'etsu Kōgen National Park.

[1] The Tone gathers tributaries and pours into the Pacific Ocean at Cape Inubō, Choshi in Chiba Prefecture.

For the sake of water transportation and flood control, extensive construction began in the 17th century during the Tokugawa shogunate, when the Kantō region became the political center of Japan.

As a result of the Fukushima Daiichi nuclear disaster radioactive cesium concentrations of 110 becquerels per kilogram were found in silver crucian carp fish caught in the Tone River in April 2012.

[6] The Tone River was an indispensable inland water link between the capitol at Edo, and later Tokyo, to the Pacific Ocean.

The remaining 220km is on detached cycling paths high up on the river bank with great views of mountains while in Gunma and large rice fields and agriculture as you approach the ocean.