Fig 7Water's phase diagrampressure on a log scaleboiling depends on pressure
Each region shows which state water takes at that temperature and pressure, and the lines between them are where two states coexist. The boiling line climbs steeply, so lower pressure means a lower boiling point: on Everest water boils at 71 °C, and a pressure cooker at twice atmospheric pressure reaches 120 °C. At the triple point ice, water and vapour all coexist. Beyond the critical point, at 374 °C and 218 times atmospheric pressure, liquid and gas stop being different.