The world's first National Park was established 1872, as a "pleasuring ground for the people". Encompassing 3,472 square miles, it contains a ancient caldera of approximately 600 square miles, and experiences 1,000-3,000 earthquakes annually. More than half of the world's thermal features are located in the park, totalling over 10,000, including 300 geysers. Over 290 waterfalls have been discovered, with the Lower Falls of the Yellowstone River being the highest at 308 feet.