Punghyul(wind cave), also known as wind hole, ice hole, ice valley, or warm hole, indicates a rock opening or break where cold air is blown in summer. In winter, warm air comes out instead. Until 2014, more than 32 air holes, 100 m high and 98 m wide, have been found north of Bukbong Peak (Nuae-bong) between elevations 900 m to 1,000 m. Wind blows from the north-eastern slope of the ridge in the morning and the north-western slope of the ridge in the afternoon. This wind cycle maintains moderate air flows within the air-holes. An influx of air in the talus region flows into the gaps between the rocks. Naenghyeol(ice hole) is created when air is rapidly cooled by an adiabatic expansion as it leaves the gaps. In winter, air is heated and becomes less dense once it flows underground. Onhyeol(Warm hole) is created when the air, much warmer than that of the atmosphere, comes out to the surface. Some wind-holes feature unusual temperature changes as well as mirages which are caused by water vapors created when cold air mass of the atmosphere collides with warm air mass. Average temperature range of the areas where wind-holes are located is 7-18℃. Diverse plants and mosses including squirrels-foot fern, hair moss, silk moss, buxbaumia minakatae, and maple-leaf ainsliaea, and protected species such as short-tailed viper snake and ussuri mamushi are observed in the areas.