Lake Kussharo fills most of the western half of the Kussharo Caldera that was formed in series of major eruptions beginning more than 300,000 years ago and ended about 100,000 years ago. This lake was formed about 30,000 years ago, and it is the largest “caldera” lake in Japan with a surface area of over 79 square-kilometers (30.5 square-miles), and a shore length of about 57 km (35 mi).
Lake Kussharo offers many recreational activities including multiple campsites, canoeing, kayaking, fishing, open air natural hot springs, and hiking along the shore.
The Kushiro River is the only river that flows out of the lake and goes through the Kushiro wetlands and empties into the Pacific Ocean in Kushiro City. There are no dams on the approximately 150 km (93 mi) long river with all different views from great nature to farmlands that makes it a mecca for canoeists. The lake may freeze over almost entirely in winter. You might see cracks and pressure ridges of ice snakes across the lake in mid-winter. Photographers from around the world come to visit the lake for Whooper Swans that are traveling from Siberia every autumn and stay at the lake for 6 months.
