The Ramsar Convention on Wetlands of International Importance Especially as Waterfowl Habitat is an international treaty for the conservation and sustainable use of wetlands.[1] Adopted in 1971, it entered into force in 1975 and as of April 2022 had 172 contracting parties.[1] Japan was the twenty-fourth party to accede, on 17 October 1980.[2] Kushiro-shitsugen was the first of Japan's fifty-three Ramsar sites as of April 2022, with a total surface area of 1,552 square kilometres (599 sq mi).[1][3]