Yongneup of Mt. Daeamsan is a montane wetland developed in the area at an altitude of 1,200m on the northwestern slope of Mt. Daeamsan (1,304m above sea level). The site is the first wetland of Korea registered in Ramsar International Convention (the Convention on Wetlands of International Importance, especially as Waterfowl Habitat) in 1997. The formation of the Yongneup has been attributed to the combined effects of geological conditions and climatic factors, primarily, mechanical weathering by the latter · subzero temperature for five months in a year with foggy days all year round. A moist and cold climate like this triggers frost wedging; water that seeped into rocks on earth’s surface repeatedly goes through the freeze-thaw cycle and eventually causes mechanical weathering of rocks. Rocks fragmented by the effects of frost wedging travel down by runoff and erode the ground surface to create hollows which later turn into wetlands. A mouth of a valley which water enters tapers abruptly so, in case the entrance get blocked by huge rocks in times of flood, surface-water and groundwater in the upstream get locked in. Once inflow becomes greater than outflow, water will be held in a place and marsh plants will grow in there; when they die, they will be heaped on the bottom of the wetland. A long duration of subzero temperature in this area helped develop peat deposits since it caused slow decomposition of the dead plants. As the sediments in the wetland dilate, they cut off the supply of surface-water and groundwater. Then the only source of nutrients of the plants living in the wetland is rainwater. The average depth of the peat deposits of the Yongneup is 1m with 1.8m at the deepest point. Given that they pile up nearly a millimeter a year, their initial formation dates back to 4,000 to 5,100 years ago. The remains of the dead plants that have not yet decomposed in the peat deposits serve as key materials in studying the changes in the vegetation and climate of the Korean Peninsula in the past. Found in the wetland are plant communities of sphagnum, umbrella sedge, willowleaf spiraea, and geranium eriostemon fisher ex DC and rare plants such as fragrant orchid, biro gentian and round-leaf sundew. Also observed in the area are 63 species of phytoplanktons, 19 species of diatoms, natural monuments like mountain goats and golden eagles, salamanders, red-bellied frogs and pieris dulcinea. The areas of Mt. Daeamsan and Mt. Daewusan including the Yongneup are regarded as valuable sources for research in plant ecology, phytogeography and systematic botany due to the occurrence of altitudinal zonation of plants and animals. The areas have been designated Natural Monument No. 246 for varying environmental conditions, e.g., distinctive landforms and exclusive climates.