Take advantage of the warmer weather by visiting any number of the hundreds of national parks across the country on April 20 for absolutely free. The National Parks Service is celebrating National Park Week by offering free entry into all of the 418 parks spread throughout the United States.

If you have never been to a national park or if it has been a while since your last visit, you may be surprised to learn about all the fun and excitement that awaits you. Here is a quick guide on some of the most popular national parks in the country and how you can spend your time in the great outdoors.

waterfall in Yellowstone National Park

Yellowstone

Yellowstone National Park is the oldest and one of the most famous parks in the U.S. The park is known for its abundant wildlife, hot springs and exploding geysers. Given its enormous size, there are plenty of things to do at Yellowstone for children and adults alike.

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Located mostly in Wyoming, the park boasts 12 campgrounds with tent and RV access, plus 300 isolated campsites. There are nearly 1,000 miles of hiking trails that offer plenty of photo opportunities. You can also bike at the park and enjoy some kayaking on one if its many lakes. If you plan on bringing your family along for the ride, the park offers specialized programs for children as well as horseback riding.

river and mountains in Yosemite National Park

Yosemite

Established in 1890, Yosemite National Park attracts many visitors for its beautiful waterfalls. But the 1,200-square-mile park also features vast meadows, large sequoias and a grand wilderness section. While sightseeing is the main attraction, there are plenty of things to keep your entire family busy.

Common activities at California’s Yosemite National Park include biking, wildlife watching, camping, fishing, horseback riding and water activities. Before booking your trip to Yosemite, check with the park for any closures due to inclement weather. Glacier Point Road, for example, is often closed until May because of excess snowfall.

fog covering trees at base of mountains in Great Smoky Mountains National Park

Great Smoky Mountains

The Great Smoky Mountains National Park is the most-visited park in the country. According to DK, the Smoky Mountains record more than double the number of tourists every year than any other location. While this is a popular destination, there are ways to avoid the large crowds. Skip out on the popular scenic highway and opt for one of the many side trails.

The ancient mountain range features one of Earth’s most widespread deciduous forests and boasts a wide diversity of life. This includes a large selection of wildflowers and black bears. When it comes to activities, visitors can enjoy camping, hiking, wildlife watching, fishing and scenic driving.

water and mountain views in Acadia National Park

Acadia

If you are looking for a good coastal drive, then Acadia National Park is right up your alley. Acadia National Park is the only one of its kind in Maine and features some dramatic views of the Atlantic coastline. You can also hike some trails on Cadillac Mountain, kayak in the ocean or partake in some amazing whale watching from just outside of Bar Harbor.

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A good strategy to see most of Acadia is to navigate the Park Loop Road, either by bike or motor vehicle. The 27-mile road has an array of different viewing points. One of the more popular stops is Otter Cliff, which overlooks a 110-foot drop. The park, of course, also features plenty of other things to do, such as camping, climbing, geocaching, fishing, swimming and bird watching.

visitor center sign in Badlands National Park

Tips for visiting a national park

Once you decide to visit a park, it is always a good idea to call or stop by the visitor center and check in. Park rangers are valuable sources of information and can tell you what type of activities are available during the time of your visit. They can also tell you if there are any construction projects going on or special events that might make navigating through the park difficult.

Speaking of the visitor center, it contains everything you need to know about the park, including typical rates and interesting places to visit. You can also find guided tours, which are a great way to get introduced to the history of the park and learn why it is significant to the region.

Grand Canyon at sunset

Free admittance on April 20

In honor of National Park Week, the National Parks Service is offering free admittance to all parks in the United States on April 20. That day coincides with National Junior Ranger Day, which is geared toward children, making the free offer perfect for families. According to Matador Network, there are other themes throughout the rest of week, including Military and Veterans Recognition Day, Earth Day, Transportation Tuesday, Wild Wednesday, Throwback Thursday, Friendship Friday, Bark Ranger Day and Park Rx Day.

You can learn more about National Park Week, plus find important information about a national park near you, by visiting Find Your Park and the National Parks website.

Images via Ian D. Keating, Mobilus in Mobili, Jeff Gunn, Thomas, Eric Vaughn, Badlands National Park and Grand Canyon National Park