The hottest of Yellowstone's geothermal features are steam vents (fumaroles). Black Growler Steam Vent has measured 199 to 280 degrees F (93 to 138 degrees C). A plentiful water supply would help cool these features; however, steam vents are usually found on hillsides or higher ground, above the basin's water supply. They rapidly boil away what little water they contain, releasing steam and other gases forcefully from underground.
Last updated: August 12, 2015