Yellowstone is the first and perhaps the greatest of the national parks in the U.S. We RV'd there in 2009 with the Old Faithful geyser in mind, but that's just one of many memorable features. A century or so ago, a geologist realized that the entire park sits inside a giant volcano that seems to be taking a breather before blowing up again. There the earth bubbles and boils, giving off sulfurous gases and a multitude of small geysers, some of them more "faithful" in their eruptions that Old Faithful. One day, Nature may assert herself and wreak total destruction over the region. I hope that will be many centuries in the future. In the meantime, it's a wondrous place.