Go Stargazing1 of 11
It's an activity as old as time, except now you have to escape to a park to get a good view of the stars. While most national parks offer unforgettable views of the night skies, those located out west provide the most stunning views.
Go to Joshua Tree National Park and look for the Milky Way, which is visible to the naked eye.
Go Exploring2 of 11
It's so simple and a free activity that you can find at every National Park. Get out of your car and on your feet to find winding trails, seemingly unearthly structures, like the spires found in Bryce Canyon, and peaceful picnic spots next to quiet, mountain lakes.
Go to Arches National Park to see Delicate Arch, one of the most famous natural arches in the world.
Have a Geocaching Adventure3 of 11
One of the most unique free things to do is go on a real-life treasure hunt. This exciting activity, perfect for all ages, will have you walking all day long, while you follow GPS coordinates to the treasure chest, also called the cache.
Go to Petrified Forest National Park to find a cache hidden along historic Route 66, parts of which are protected within the boundaries of the national park.
Enroll in a Junior Ranger Program4 of 11
All of the Junior Ranger Programs offered through the national park system are free, and most allow the entire family to participate. If they charge for the activity booklet at the park—price ranges from $.50 to $1.00—print it at home before you go.
Go to Great Sand Dunes National Park on Junior Ranger Day, when 15 activity stations are set up, allowing children to work closely with rangers and naturalists.
Start a Snowball Fight5 of 11
Some national parks are more stunning in the winter than the summer. Covered in snow, you can enjoy free things like snowshoeing and cross-country skiing. Of course you'll have to pay for the cost of rentals if you don't have the right equipment. So, why not have a family-friendly snowball fight, instead?
Go to Acadia National Park, where plenty of snow falls throughout the winter. After the snowball fight, erect your own snow fort or make a snowman.
Look for Birds6 of 11
Grab your binoculars and bird identification book, and head to the nearest national park. Most parks are home to a variety of bird species, making it exciting for both beginner and expert birders alike.
Go to Great Basin National Park to see more than 136 bird species, ranging from common to rare. If you spot something that's not listed on this checklist from the national park system, tell the local park ranger.
Snap Photos7 of 11
You can't take the view from the top of a mountain or a bright trailside flower home with you, but you can snap a few photos to remember how stunning the scenery was.
Go to Great Smoky Mountains National Park, where more 1,660 kinds of wildflowers bloom, which is more than any other park. These beauties make for the perfect photography subject.
Get a History Lesson8 of 11
Many national parks are built around historical monuments, or have erected museums to commemorate historic events. If you're a history buff, this is one of the free things you shouldn't pass up.
Go to Dry Tortugas National Park and take a self-guided tour of Fort Jefferson. Be sure to check out all the rooms and take in views from the top.
Listen to a Nature Talk9 of 11
Sit in on a nature talk to learn more about the park you're visiting. These talks can range from 15 minutes to an hour, and some include a guided hike. Either way, it's an interesting way to spend the afternoon.
Go to Big Bend National Park for a nature talk or guided hike, and learn about the natural and cultural history of the park. Check NPS.gov for an updated schedule of events.
Take Scenic Drive10 of 11
Stay in your car and hop on a scenic byway; there are 126 total in the U.S. Each road was chosen based on its uniqueness, culture, history and scenic landscape. This is one of the best free things to do if you have an infant that can't go on a hike or spend much time in the sun.
Go to Shenandoah National Park and take the 105-mile Skyline Drive. Go in the fall to witness unforgettable colors or in spring when wildflowers are in bloom.