Few places in the world can match Yellowstone National Park's collection of accessible wonders—a "window on the earth's interior" is how one geophysicist described it. As you visit the park's hydrothermal areas, you'll be walking on top of the Yellowstone Caldera—a 28-by-47-mi collapsed volcanic cone. The geyser basins, hot mud pots, fumaroles (steam vents), and hot springs are kept bubbling by an underground pressure cooker filled with magma. Above ground, the terrain yields rugged mountains, lush meadows, pine forests, free-flowing rivers, and the largest natural high-elevation lake in the United States. More »
