The Santerno is a river in Romagna in northern Italy. It is the major tributary of the Reno River. In Roman times, it was known as the Vatrenus (small Renus), although, in the Tabula Peutingeriana, it was already identified as the Santernus.

The Santerno is a river in Romagna in northern Italy. It is the major tributary of the Reno River. In Roman times, it was known as the Vatrenus (small Renus), although, in the Tabula Peutingeriana, it was already identified as the Santernus.