No doubt by now, you know that the National Park Service (NPS) is celebrating its 100th birthday this year.

The extra media attention on the milestone has been credited by many outdoor brands and retailers for a boost in business in 2016.

And this week, they may get one final bump as the NPS celebrates its actual birthday today, August 25. To blow out the candles, all National Parks will be free for the extended weekend, through Sunday, August 28.

The fee-free days are part of a total of 16 free NPS days in 2016 to celebrate the centennial anniversary.

Two more free days are coming up this year on September 24 (National Public Lands Day) and November 11 (Veterans Day). In addition, any fourth grade student can get a free annual pass through the “Every Kid in a Park” program, and active duty military and citizens with a permanent disability can also get free passes.

“National parks are America’s best idea, and there are more than 400 parks available to everyone, every day,” officials said. “The fee-free days provide a great opportunity to visit a new place or an old favorite, especially one of the 124 national parks that normally charge an entrance fee.”

The fee waiver includes entrance fees, commercial tour fees and transportation entrance fees. Other fees such as reservation, camping, tours, concession and fees collected by third parties are not included unless stated otherwise.

Photo by David Clucas