The world's largest active geyser has erupted three times in the past six weeks and scientists don't know why.
The latest event, which was photographed by a visitor to Yellowstone National Park in Wyoming, occurred on Friday.
The last time there was a major eruption of the Steamboat Geyser was in 2014. According to the U.S. Geological Survey, all of this year's eruptions have been smaller than the 2014 event.
Although scientists can't explain why the geyser has become so active, they don't believe the eruptions in the northwest section of the park signal pending trouble with the supervolcano beneath Yellowstone.
"There is nothing to indicate that any sort of volcanic eruption is imminent," Michael Poland, head of the USGS's Yellowstone Volcano Observatory, told Reuters.
Steamboat, located in the park's Norris Geyser Basin, can shoot a column of hot water up to 300 feet into the air. Its eruptions have always been unpredictable.
Yellowstone's volcanic plateau is home to the world's largest, most spectacular hydrothermal system of colorful springs, thermal ponds and geysers. The park is on top of a volcanic caldera — or crater — and vast underground chambers of magma flow miles beneath the surface. Geysers erupt when magma heats water that has seeped underground.
The park's most famous geyser, Old Faithful, is a fraction of the size of Steamboat and erupts every 45 to 125 minutes.
As for the Steamboat Geyser, Poland told The Washington Post: "It's cool, it's exciting, it's neat. It's nothing to be afraid about."
An explanation about Yellowstone's supervolcano can be found in National Geographic.