Bats, Volcanos, Crocs: 15 Hair-Raising National Park Adventures

This year marks a century since the establishment of the National Park Service, the organization preserving conservation forests, mountains, gardens, lakes, wildlife and rivers in national parks across America.

The second century of stewardship and the celebrations marking it will officially begin August 25 but you don't have to wait until then to enjoy the riches these national "treasures" offer. You get to visit all parks for free during National Parks Week, April 16-24.[slideshow:83208]

Recent studies have shown that merely a walk in the park can calm the mind while changing the way the brain works in ways that improve mental health.

So, the benefits from being outside, the chance to save money and the nicer weather are all good reasons to discover new adventures in America's parks, which have some of most beautiful and unique landscapes in the country.

Whether you travel alone, with friends or with a large family, there are quests for everyone. Some are quite challenging, others can be are very scary or intriguing. You can go wolf-tracking, sandboarding, wildlife watching, or on a hot air balloon ride.

With help from the National Park Foundation, we compiled a list of the best exploits.

Click here to see the 15 Hair-Raising National Park Adventures

More readings: 

16 Most Spectacular National Parks to Visit this Spring

The Most Visited National Parks

The Most Dangerous Places in National Parks