Besides producing hot springs, the underground geothermal energy is hot enough to boil water and create steam. From hills above the water table, this steam issues from cracks in the rock, producing another feature of the Tatun hot spring area-steam vents.
除了豐富的泉脈，當地底溫度過高，水被蒸發成水氣噴出，或是裂隙開口高於地下水層，只能讓蒸汽冒出，就成為大屯山溫泉之外的另一個火山景觀──噴氣孔。