Happy Earth Day! Get ready to celebrate the day by diving into nature all week long.

This week, the National Park Service is celebrating National Park Week from April 20-28.  To commemorate the week, the service is offering free admission to all national parks, starting today and ending Friday, April 26. Many parks are planning special programs, such as day-long National Junior Ranger activities for children.

There are over 400 national park units around the country. And now, thanks to the addition of First State National Monument in Delaware, there is officially a park service unit in every state. So everybody can get out and enjoy the nation's parks. And this week, you can do it for free.

Hit one close to home or make a plan to visit one far away that you've always wanted to see.

You can check out Cajun Music Jams at Jean Lafitte National Historical Park and Preserve in Mississippi, go birding with a ranger at Padre Island National Seashore in Texas, or watch the National Park Week Film Series at George Washington Carver National Monument in Missouri. It's your choice. And this week, it's all free.

Need help deciding where to go? Check out this list of special National Park Week activities.

Celebrate National Park Week with free fees
You can celebrate Earth Day all week long with free admission to any national park.