Which country has the world's largest hot-spring system at Yellowstone?

The United States is home to Yellowstone, the world's largest concentration of hot springs and geysers.

Yellowstone National Park lies mainly in Wyoming, with smaller portions in Montana and Idaho. It was established in 1872 as the world's first national park. The park sits above a large volcanic system whose heat drives its famous hydrothermal features.

Yellowstone contains more than half of the world's active geysers. Old Faithful is the most famous, but it is not the largest or most regular geyser in the park. Steamboat Geyser has produced the world's tallest recorded water eruptions, although its intervals are unpredictable.

The park also protects a vast ecosystem containing bison, elk, grizzly bears, wolves, and many other species. Its colourful hot springs result from heat-loving microorganisms and mineral deposits. Yellowstone is often called a supervolcano, but that informal label refers to the scale of its volcanic system rather than a separate volcano with a conventional cone.