Kiritappu Marsh is one of the largest marshlands in Japan, covering an area of 3,168 ha. It is well known as a provincial natural park and was recognized as a registered wetland at the Conference of the Parties to the Ramsar Convention on Wetlands of International Importance, especially as Waterfowl Habitat, held in Kushiro City in June 1993.
It is also known as "Flower Marshland" because of the many flowers that bloom in summer and fall. In winter, the marsh is tinted white by snow, and cranes and Steller's sea eagles can sometimes be seen.