Yellowstone National Park, Wyoming

The world's oldest national park has been described as the "uplands of Hell."  Over 10,000 mud pools, hot springs, geysers, and fumaroles release heat and steam from below the earth's surface.  Old Faithful is perhaps the best known geyser and sends a steaming plume of spray over 180 feet in the air every couple of hours.  It did not disappoint, and we were there for the 4:00 p.m. explosion.  Meanwhile, Castle Geyser was spewing a continuous spray of steam, cinder, and scalding water just down the hill-- a more impressive display, but not one tourist can count on seeing.  It was a bit surreal to walk in this steaming landscape, and easy to see why it is on the list of 1000 Places To See Before You Die.