That's a geyser. It's kind of a hot spring that spurts up water and steam every so often. It works kind of like a coffee percolator. Water in passages deep down where the rocks are hot is heated up to the point where it would normally turn into steam, except it doesn't because of the pressure of the other water on top of it, so it gets really hot and it expands and it pushes some of the colder water out of the top. That relieves the pressure, and all of a sudden the hot water turns into steam, and POW! It erupts out along with all the colder water on top. Then more water flows down into deep passages and the whole thing starts over again. Most geysers are located in Wyoming, New Zealand, or Iceland. The word "geyser" originated in Iceland, from their word, "geysa," meaning "gush." Geysers are usually very unpredictable about when they erupt. The most famous exception is a geyser called Old Faithful, in Yellowstone National Park in Wyoming, which erupts every 64 minutes, uh, give or take about 3 minutes. It looks like this one goes off a lot more often than that.