Hawaii Volcanoes National Park
This is one of the few places in the world where travelers can visit a live volcano. At this UNESCO World Heritage Site, the major attraction is the wildly active Kilauea volcano, and its simmering-but-sleepy neighbor, Mauna Loa. The park encompasses the summit calderas of both of these volcanoes, along with a rain forest, a desert, ancient petroglyphs... Hawaii's volcanoes produce slow eruptions, not violent explosions. Rather than fleeing, people show up and bring a picnic! The show is really something at night.