Inside and out, there is so much free stuff to do with your family this weekend! If you haven't already done so, you can still print out your ticket for free museum day and go check out your favorite local spot. If you'd rather be outdoors, make a plan to visit a local park and enjoy the free admission there too on Sept. 22.

Why the freebie at the national parks? It's the 25th anniversary of National Public Lands Day, a day set aside to encourage folks to volunteer on their public lands and enjoy the great outdoors. Now don't worry; you don't have to volunteer to get in for free.

"National Public Lands Day is an opportunity for us to celebrate and make a difference in America's open spaces, from small neighborhood parks to large national parks," said then National Park Service Director Jonathan B. Jarvis. "We are fortunate that more than 600 million acres of public land, including national parks, provide all of us with cherished places where we can go to recreate, exercise, learn about the past, and connect with nature."

More than 180,000 people are expected to plant trees, build and maintain trails, remove invasive plants, remove trash, and improve and restore 2,200 public sites throughout the country. Many national parks are hosting volunteer events and celebrations. Check out the website link above for more details and to find a volunteer opportunity in your area.

In addition to the national park service, federal agencies waiving fees on Saturday include the U.S. Fish & Wildlife Service, the Bureau of Land Management, the Bureau of Reclamation, the U.S. Army Corps of Engineers, and the U.S. Forest Service.

If you miss this one, don't worry. The National Park Service will also waive entrance fees from Nov. 10-12 in commemoration of Veterans Day.

Editor's note: This story has been updated since it was first published in September 2013.

Free admission to national parks this Saturday
Celebrate National Public Lands Day with a free visit to one of your favorite national parks or forests.