Of the three, however, the most acidic springs are the blue sulfur ones, and it is these that are the Peitou thermal valley's speciality. Their water is clear, with a hint of blue-green, and contains traces of radioactive elements-it is said that these springs are especially therapeutic.
而強酸性的青磺則是北投地熱谷的特產，水質透明微綠，帶有微量放射元素，據說特別具有養身療效。