The Biwako Marathon or Lake Biwa Mainichi Marathon is held annually in March in Otsu. It starts (at 12:30 pm) and finishes at Ojiyama Stadium in central Otsu, near Otsu Shiyakusho-mae Station on the Keihan Ishiyama-Sakamoto Line.

Known as one of Japan'a major marathons for top male runners, the Lake Biwa Marathin's 42.195 km course goes along the lake shore and Seta River. The terrain is mostly flat. Before the start of the marathon, there are PR booths near the stadium entrance.