The unpredictable Yellowstone National Park "Steamboat" geyser erupted for the first time in eight years.

The world's tallest geyser, "Steamboat," sometimes goes decades without erupting. It doesn't tend to stick to its habits, in the 1960s it went off 29 times in one year, CNN reported.

The geyser makes a grand appearance when it does decide to erupt, it shoots up to 400 feet into the air, and the event can last as long as 40 minutes. After the show, steam continues to billow out for hours.

The notorious geyser decided to erupt on Wednesday, after sitting dormant for eight years.

"We estimate this eruption was about 200 to 300 feet high, and then it just steamed for about 24 hours," Yellowstone spokesman Dan Hottle, said.

It took park rangers over two hours to make it there, but people on the observation deck saw the eruption and photographed it.

Rob Long had the rare opportunity to watch Steamboat's show, the Los Angeles Times reported via the Associated Press.

"It was an amazing experience. This thing sounded like a locomotive," Long said. "Everybody was frantic, taking pictures. People were running down there trying to get to it before it went away, and park rangers were running around trying to gather up people so they didn't get too close."

Park staff rely on electronic heat sensors to tell them when one of the geysers is erupting, CNN reported.

"When it jumps up, we know we've had an eruption shoot up," Hottle said. With Steamboat, "we saw that jump and then some folks called that it happened."

People are already wondering when the next eruption will be.

"For us, it's exciting. Every time you're down there, you wonder if that'll be the time that it erupts," Hottle said.

The Yellowstone National Park contains about 300 geysers, that's over 50 percent of what exists globally.

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