Yellowstone, as a whole, possesses close to 60 percent of the world's geysers. The Upper Geyser Basin is home to the largest numbers of this fragile feature found in the park. Within one square mile there are at least 150 of these hydrothermal wonders. Of this remarkable number, only five major geysers are predicted regularly by the naturalist staff. They are Castle, Grand, Daisy, Riverside, and Old Faithful. There are many frequent, smaller geysers to be seen and marveled at in this basin as well as numerous hot springs and one recently developed mudpot (if it lasts).