April 21–29 is National Park Week, and the celebration kicks off with a free day at all of America’s national parks.

Get the sunscreen and camping gear, and load up the station wagon.All 417 national parks are free to enter this Saturday. The annual tradition marks the beginning of National Park Week, with special events happening at parks across the country.

Saturday marks the second of four national park free days this year. And the next two won’t come around until autumn.

National Park Free Day April 21st

Of the 417 national parks, 117 charge entrance fees: $7–15 for individuals and $15–30 for vehicles.

Despite the free admission, parks will still collect fees for camping, boat launches, transportation, and tours.

Enjoy this opportunity to see America’s greatest national treasures at no cost. Come summer, national park fees go up!