Castle Geyser. Castle has an intense eruption that lasts 20 minutes or so before the water has been eliminated and it begins to roar like a steam train for 30-40 minutes.

I was sitting on a wooden bench in Yellowstone National Park, overlooking the violently steaming Castle Geyser with two dozen other tourists when my partner, Brian, struck up a conversation.

Shortly after Castle Geyser, turn right toward Crested Pool and Sawmill Geyser. Afterward, take another right toward Geyser Hill, eventually ending back at Old Faithful.

A bison roams in front of Castle Geyser in the Upper Geyser Basin at Yellowstone National Park, Mont., on Sept. 25, 2023. (AP Photo/Hannah Schoenbaum) Show more Show less .

A bison roams in front of Castle Geyser in the Upper Geyser Basin at Yellowstone National Park, Mont., on Sept. 25, 2023. (AP Photo/Hannah Schoenbaum) ...

Castle Geyser is a cone geyser in the Upper Geyser Basin of Yellowstone National Park. George D. Lepp/Getty Images. Previous studies have suggested the partial melt fraction was between 5% and 15% ...

The Upper Geyser Basin, where the Semi-Centennial Geyser is located, includes many other famous geysers and hot springs, including Old Faithful Geyser, Steamboat Geyser, Castle Geyser and Grand ...

(Neal Herbert/National Park Service via Flickr) The Milky Way over Castle Geyser in Yellowstone National Park in July 2016. (Neal Herbert/National Park Service via Flickr) Guest.