Summer is an amazing time to get outdoors and see the world. The United States is full of national parks established to preserve wildlife and allow access to some of the nations most beautiful sites. So, while you are out smelling the roses, here are a few unique national parks you should check out.

1. Mammoth Cave National Park

Located in central Kentucky, Mammoth Cave National Park contains the largest network of natural caves in the world, and it's taken nearly 100 million years to form. And you think your grandpa's old.

2. Great Sand Dunes National Park

The people of Colorado have yet another way to get high. Great Sand Dunes National Park boasts the largest sand dunes in North America, which can reach up to 750 feet. This beautiful park is perfect for hanging out on the beach or going for a hike, though the sand does get up to 150 degrees Fahrenheit

3. Hawaii Volcanoes National Park

If you still haven't quite thawed from winter yet, or you can't get enough of the summer heat, then Hawaii Volcanoes National Park is probably for you. Established in 1916, the park contains two very active volcanoes, Mauna Loa and Kilauea. It has given scientists very interesting clues about the formation of the Hawaiian Islands. Fun fact, the last eruption to occur at Hawaii Volcanoes was in March 2008.

4. Mesa Verde National Park

More than 3,000 years ago, the native Pueblo people inhabited what is now Colorado, leaving some interesting structures that can be found at Mesa Verde National Park. Scattered throughout the park are several cliff dwellings (among the 5000 archaeological sites) that contain living spaces and other artifacts.

5. Bryce Canyon National Park

Last but not least comes Bryce Canyon National Park. Located in the beautiful state of Utah, you can find one of the most stunning national parks the United States has to offer. Bryce Canyon was formed not by a single stream, but stream shoot-offs, creating thousands of tiny rock spikes, called "hoodoos". Overall, I'd say this park looks pretty Gneiss.

Sources:

basicplanet.com

http://wilderness.org/blog/americas-best-kept-secr...

www.nps.gov