ヴァルダイ丘陵
The Syas () is a river in Lyubytinsky District of Novgorod Oblast and Tikhvinsky and Volkhovsky Districts of Leningrad Oblast, Russia. The Syas flows from the Valdai Hills north into Lake Ladoga. The town of Syasstroy is located at its mouth. It is long, and the area of its basin . The largest tributary of the Syas is the Tikhvinka (right).