CNN.com - Hidden Treasures

"Assateague Island is well known for its wild horses, which are actually descendants of domesticated animals that have reverted to a wild state. The National Park Service says the most plausible explanation for how the horses got there is that mainland owners brought them to barrier islands like Assateague to avoid 17th-century fencing laws and taxation."

Located in south central Oregon, Crater Lake National Park ranks as the fifth-oldest national park in the United States. The six-mile-wide crater formed nearly 7,000 years ago when Mt. Mazama erupted and collapsed. An old Native American legend tells the story of a battle during which Chief Skell of the Above World destroyed the home of Chief Llao of the Below World, Mt. Mazama.

Located in southeastern Utah, Bryce Canyon National Park is dominated by a spectacular series of natural horseshoe-shaped amphitheaters carved out by millions of years of erosion.

Kentucky's Cumberland Gap is a major break in the Appalachian Mountains that animals, Native Americans and European settlers used as a path through the peaks. The Cumberland Gap cuts between the Cumberland and Brush Mountains, both of which are rugged chains with high cliffs.