Sone, a river of British India, a southern tributary of the Ganges, rises in the highlands of the Central Provinces, in lat. 22° 41' N., lon. 82° 7' E., near the source of the Ner-budda, and falls into the Ganges 28 m. above Patna, after a course of upward of 450 m. The general direction of its flow is northeasterly, through Jubbulpore, Rewah, and Behar. All its important tributaries come from the south. In the highlands it flows through narrow valleys, but lower down they widen into alluvial plains, which are well cultivated, and yield cotton, indigo, and sugar cane. It is about 3 m. wide at its junction with the Ganges, but the navigation is of little importance above Daudnugur, about 60 m. from that point, where the river is 10 or 12 ft. deep in the rainy season, but at other times nearly dry. Coal is found upon the banks of its upper course, and agates and carnelians occur. Work is now (1876) in progress on the Sone irrigation project for supplying water to about 2,000,000 acres in the Patna division of Bengal, by a dam across the river, and other works.