(CNN) - Looking for something fun and free? Head out to America's national parks.
The National Park Service is offering free admission to all its parks all week long.
The deal is from Saturday, April 21 until Sunday, April 29.
The NPS also invites you to take a picture of yourself at a national park and post it on their web site.
Visit www.nationalparkweek.org for more information.
By the way, every U.S. state except Delaware has at least one national park.