琵琶湖
Lake Biwa, the largest freshwater lake in Japan, covers and is located at the center of the Shiga Prefecture. The north part of the lake reaches a depth of , and the south part of the lake near Ōtsu is much shallower and reaches a depth of . Lake Biwa provides water for the industrial areas of the Kansai Region, irrigation and drinking water in the Shiga area. The lake has been a travel destination since ancient times, and continues to support the tourism industry of the prefecture. The lake is protected as part of Biwako Quasi-National Park. Lake Biwa is home to the Lake Biwa Marathon, which started in Osaka in 1946, and moved to Lake Biwa in 1962. It is considered to be the oldest marathon in Japan.