The Ishikari River (石狩川, Ishikari-gawa), at 268 kilometres (167 mi) long, is the third longest in Japan and the longest in Hokkaidō. The river drains an area of 14,330 square kilometres (5,530 sq mi), making it the second largest in Japan, with a total discharge of around 14.8 cubic kilometres (3.6 cu mi) per year.
It originates from Mount Ishikari in the Taisetsu Mountain Range and flows through Asahikawa and Sapporo. Major tributaries of the river include the Chūbetsu, Uryū, Sorachi and Toyohira rivers. Until 40,000 years ago, it flowed into the Pacific Ocean near Tomakomai. Lava from the volcanic Shikotsu mountains dammed the river and moved its mouth to the Sea of Japan.