Location: N58° 21` 6.00", E25° 35` 38.0"
Lake Viljandi is situated in Viljandi county lying in the ancient valley on Sakala uplands. The lake is ling, narrow deep and has high shores. The average depth of the lake is 5.6 metres and the deepest point is 11 metres. It is 4.6 km long and 450 metres wide. The shores are muddy and slippery and sometimes even 30 meters above the level of water. A lot of fish live in the bulrush -and -reed-infested area: roach, perch, pike, bream. The Köstri and Valuoja streams flow into the lake and the Raudna river flows out. The waters of Raudna river end up in the Riga Bay. It is believed that centuries ago there was a waterway for cargo ships from Pärnu city to Lake Peipsi through Viljandi and Võrtsjärv Lake.