The largest acidic geyser in the world is erupting again at Yellowstone National Park after several years of dormancy, according to the U.S. Geological Survey. The largest acidic geyser in the world is erupting again at Yellowstone National Park after several years of dormancy, according to the U.S. Geological Survey. Echinus Geyser, a 66-foot geyser pool located in the hottest and most dynamic part of Yell... [3167 chars]