Largest concentration of geysers

According to UNESCO, Yellowstone National Park, which lies mostly within the borders of Wyoming, USA, contains more than 10,000 geothermal features – at least half of the world's known examples. The park's extensive, intact ecosystem is home to thousands of hot springs, mudpots and fumaroles, and boasts in excess of 500 geysers – two-thirds of the planet's total – with up to 250 of those active. Geysers are hot springs of boiling water that erupt periodically into the air as the underground water flashes to steam and expands up to 1,500 times its original volume.

Yellowstone was established in 1872, making it the oldest national park, and covers 9,000 km2 (3,475 sq mi) of the American West. It occupies Wyoming (97%), Montana (2%) and Idaho (1%).

The park is also home to Steamboat Geyser, the world's tallest current geyser, which reaches heights in excess of 90 m (295 ft); its tallest recorded jet was 137 m (449 ft) on 19 July 2020.