The highest concentration of geysers and hydrothermal springs in the world are located here in this corner of Yellowstone National Park in Wyoming, called the Upper Geyser Basin. They include what is perhaps the most famous geyser of them all: Old Faithful. But the Upper Basin contains many other geysers as well, including the tallest predictable geyser (Grand Geyser) and the most voluminous geyser (Giant Geyser). Yellowstone contains about 300 geysers, about two-thirds the number in the entire world.
