As the fourth-largest country in the world, the United States has a vast assortment of picture-perfect natural scenery to flaunt. From the Alaskan Tundra to the Gulf of Mexico, Niagara Falls to the Hawaiian Islands, the contrasts between the 50 American states and five territories are fascinating and sometimes enigmatic.

Geological, physical, chemical, and biological phenomena have rational explanations, but some are so rare they seem to be a figment of a science fiction screenwriter's imagination. Nonetheless, understandable or not, they do—unmistakably—indulge the senses.

From features in national parks to regional quirks, Stacker compiled a list of 20 of the strangest natural phenomena in the U.S. Anyone hoping to catch a glimpse of these phenomena must remain mindful of the risks they face in the wilderness and also of the damage they could inflict on the environment. Government and community organizations manage the grounds where many of these natural happenings occur—and are often available to guide visitors through their journey.

So, revel in that which only nature can offer, buckle up for a jaw-dropping adventure, and enjoy the ride.

LOOK: 20 of the strangest natural phenomena in America

From fire rainbows to bioluminescent bays, America is home to some truly bizarre natural phenomena. See Stacker's list of 20 of the strangest natural phenomena in the U.S.