The highest concentration of geysers in the world is found here in this corner of Yellowstone National Park, 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 500 geysers, roughly two-thirds the number in the entire world.