One of more than 200 caves in Sequoia and Kings Canyon, Crystal Cave is composed largely of marble, the result of limestone being hardened under heat and pressure. It contains several eye-popping formations. There used to be more, but some were damaged or obliterated by early-20th-century dynamite blasting. You can only see the cave on a tour. The Daily Tour ($15), a great overview, takes about 50 minutes. To immerse yourself in the cave experience—at times you'll be
crawling on your belly—book the exhilarating Wild Cave Tour ($130). Purchase Daily Tour tickets at either the Foothills or Lodgepole visitor center; they're not sold at the cave itself.