Geothermal features, which include geysers, hot springs, steam vents called fumaroles, and boiling mud pots, are found on nearly every continent. Yellowstone National Park in Wyoming contains the world's largest collection: nearly 10,000 such features lie within its 2.25 million acres. In this video segment adapted from ZOOM, a young guide offers viewers a tour of the park and explains how Earth's internal heat fuels geothermal formations. The tour makes it clear why millions of people visit Yellowstone each year to witness the park's explosive displays and colorful deposits.