Lake Kussharo is a gigantic cobalt blue lake inside the Kussharo Caldera, Japan's largest caldera. It is located 2.1km west of Kawayu Hot Springs, the 6th largest lake in Japan (and the largest caldera lake) with a circumference of 57km, an area of 79.3km2 and a depth of 117.5m at its deepest point. The island rising from the lake is Japan's largest island in a freshwater lake, with a circumference of 12km and an area of 5.7km2. It is famous as a resort where you can enjoy camping, fishing, water sports such as yachting and windsurfing, and bathing in the hot springs. During the freezing winter, the entire lake freezes over. The ice expands and contracts depending on the temperature, making creaking noises as the surfaces rub together. This is called "omi-watari" (crossing of the gods). The ground heat and hot spring in some areas of the lakeside cause some of the ice to melt, attracting 400-500 swans every year.