Sió is an artificial channel in central Hungary. It is the outlet of Lake Balaton. It flows out of the lake in the city Siófok. It flows along the city Szekszárd, and a few km east of this city it flows into the river Danube. The river Sió flows through the Hungarian counties Somogy, Fejér and Tolna.
Coordinates: 46°20′N 18°53′E / 46.333°N 18.883°E