Nestled amidst staggering hills and prairie lands, Wind Cave is a site soaked in mystery. Located 10 miles north of the town of Hot Springs in western South Dakota, the park was established in 1903 by President Theodore Roosevelt. It was the seventh U.S. National Park and the first cave in the world to be considered a national park. Touted as one of the longest cave systems around the globe, the park shelters a multitude of animals like bison, elks and antelopes which roam free in the vast fields. Studded on the recesses of the cave is a fascinating fusion of crystalline shards and displays of boxwork, an uncommon type of mineral structure which is a subject of much geological interest. Interspersed with crisscrossing trails, pathways and roaring ravines, Wind Cave National Park is awash in striking semblances of nature, history and geology.

This UNESCO World Heritage Site is the United States' most-visited national park. Sprawled across a luxuriant expanse of 522,419 acres (211,416 hectares), the Great Smoky Mountains National Park is split down the middle by the State Line that demarcates the territories of North Carolina and Tennessee. The park is renowned the world over for its remarkably diverse flora and fauna, sheltered by a series of ridges drenched in the cool spray of cascading waterfalls. Dressed in a blanket of dense forests and wildflower-laden meadows stitched together by babbling streams and gushing rivers, spellbinding vistas lay around every corner amid the ancient Appalachian mountains. The scenery transitions with the seasons from the vivid green of summer and the riotous colors of spring to the warm cast of fall and the white shroud of winter. Amid this vibrant and varied landscape, close to 80 historic buildings preserve the southern Appalachian mountain culture, of which the pioneer homestead at Cades Cove is just one. With ample opportunity for activities like hiking, biking, fishing and more, the ethereal allure of the Great Smoky Mountains is impossible to ignore.

Dubbed the "Crown of the Continent Ecosystem" by famous explorer George Grinnell, Glacier National Park is a truly stunning slice of pristine American wilderness spread across more than one million acres. Over 1000 species of plants and hundreds of species of animals have made this park their home, occupying diverse ecosystems like crystal clear lakes and rough grassland. Once the site of massive glacial action, the park features towering mountains such as Going-to-the-Sun and Chief Mountain, impressive landmarks that rule over the untouched nature below. The region retains significant cultural ties to the Blackfeet Tribe, whose reservation lies to the East of the park's sweeping mountain range.

Sheltered in the heart of Colorado's pristine countryside, the Black Canyon of the Gunnison National Park is one of the state's largest nature reserves, generously spread over 30,750 acres (12,440 hectares) of virtually-untouched semi-arid wildernesses. The park gets its name from the Gunnison River that bisects its rock-strewn lands, sustaining the wildlife that takes shelter under its protection. Some of the most-endangered of the national park include the great horned owl, the black bear, the mountain bluebird, the canyon wren and the peregrine falcon. Laden with spectacular geological marvels such as the Black Canyon, its dramatic outcrops, and stunning escarpments are a sight to behold.

Mammoth Cave is the world's longest cave system; a labyrinthine network of subterranean passages, vast caverns and vertical shafts. Typical of karst topography, the cave and its myriad formations are a testament to the forces of nature; a tribute in limestone, each layer a facet of the earth's evolution. Forests of stalactites and stalagmites are found alongside the finest gypsum flowers like otherworldly glass art while babbling streams and subterranean lakes brim with crystal-clear water. Home to one of the largest populations of cave-dwelling wildlife, over 130 species reside within the shadowy depths of the Mammoth Cave. The National Park envelops over 400 miles (640 kilometers) of surveyed passages enclosed by the cave itself, as well as part of the Green River Valley and the hills of south-central Kentucky. Apart from guided tours of the cave, activities like kayaking, hiking, horseback riding and biking can also be indulged in at the Mammoth Cave National Park. An isolated world of many mysteries, the Mammoth Cave National Park is recognized as a UNESCO World Heritage Site.

A sea of pillars in shades of ochre and red stretch as far as the eye can see in Bryce Canyon. Called hoodoos, these pillars are shaped by eons of wind and water erosion into intriguing shapes that defy logic. The most spectacular formations are located in the Bryce Amphitheater; its castles, steep pink cliffs and towering pillars an expression of nature's stark beauty. At dawn and sunset the amphitheater is awash in a prism of warm hues. Inspiration Point, Sunrise Point and Bryce Point are a photographer's delight, promising breathtaking vistas that soothe the spirit and fire the imagination.