Bayan is in Yangmingshan National Park. The hot spring pools are well maintained by the local. Pools are made out of sandbags and rocks by them, and there is a wide selection for water temperature. The hot spring water is milky white and very sulfery. Its pH is 2~3, the same acidity as lemon juice or dilute sulfuric acid; It is recommended to take off all metal wearings before the hot spring bath. The hot spring pools exist all year long. All creeks and hot springs in Yangminshan Park are banned by YMS headquarters, yet Bayan Hot Spring is very popular on weekends. Sometimes police officers come and you might get fined for 1500NT dollars.