Sumeunmulbaengdui is a natural mountainous peat wetland on Halla Mountain or 'Hallasan', a shield volcano on Jeju Island and the largest mountain in the Republic of Korea. The Site is unique in the biogeographic region because of its geology and method of formation. It plays an important role in storing and recharging groundwater since Jeju, being a volcanic island, is short of water throughout the year due to irregular precipitation and low infiltration rate. Mostly, water is recharged by groundwater from wetlands, including Sumeunmulbangdui and the three other Ramsar Sites on the island. The geographic features of these Sites are all different: Sumeunmulbangdui is situated on the slope of the volcano, surrounded by six parasitic cones. The Site’s bedrock has a high water-retaining capacity and functions as a natural filter. The name ‘Sumeunmulbaengdui’ which means ‘a field covered with water and hidden by parasitic volcanoes’ in the local dialect, reflects the rarity of the site and surrounding landscape.