Norris Geyser Basin

Norris is the hottest and most changeable of Yellowstone's thermal areas. It sits where three major faults cross, outside the youngest of the park's calderas but inside the oldest and largest, and a scientific drill hole here found 459 degrees Fahrenheit just 1,087 feet down, the highest temperature yet recorded anywhere in the park. Much of the water is acid. Earthquakes and mineral deposits keep rerouting its plumbing, so features go quiet, new vents break open, and a pool seen one summer may be a hissing hole the next; Congress Pool has been both.

Steamboat Geyser, in the Back Basin, is the tallest active geyser in the world. Its major eruptions throw water more than 300 feet for up to forty minutes and then roar with steam for hours, and the gaps between them have run from three days to fifty years. After a long quiet spell it woke on March 15, 2018, erupted thirty-two times that year and forty-eight times in each of the next two, and went on erupting for years afterward. When it goes, nearby Cistern Spring drains, a link confirmed in 1983. Echinus Geyser, a short walk away, is the largest acid geyser known.

The stone-and-log Norris Geyser Basin Museum, built in 1929 and 1930 as one of the park's first trailside museums, is a National Historic Landmark, and the 1908 Norris Soldier Station by the campground now holds the Museum of the National Park Ranger.