The Suao Cold Spring is a kind of carbonic acid spring. It comes from a thick underground limestone layer active in the Tertiary Period, and is blessed by the abundant rain of Yilan. Today, the surface layer is covered with slate and sand stones.The Suao Cold Spring was first discovered, studied and utilized by Japanese soldiers in 1928. It is the one and only cold spring in Southeast Asia and is regarded as the two most precious underground treasures of the Lanyang Plain along with Jiaoxi Hot Spring.The spring’s average water temperature is below twenty-two Celsius degrees, and the water is clear, drinkable and bathable. Because it tastes sweet and contains lots of carbon dioxide, the locals use it to make yokan, a Japanese dessert, as well as cold spring soda. They are both worth a try.At the cold spring area, there is an outdoor public pool, several private bathing pools and a leisure park. While you may feel cold the moment you get into the water, in no more than five minutes, you shall feel warm from top to toe. The small bubbles coming from the bottom of the pool are quite fun. Some people say they feel like bathing in sugar-free soda water.It is said bathing in the cold spring is good for soothing skin diseases, and drinking it can heal stomachache. Be sure to try the cold spring and see if it is as marvelous as people claim it to be.