I just read an article about the "America the Beautiful" National Parks and Federeal Recreational Lands Pass.
Basically, any active-duty service member and dependents can get a free annual pass to National Parks. The pass is usually $80, so this is a pretty awesome deal - and just in time for summer!
More info here: https://store.usgs.gov/pass/military.html
Re: Military Families get into National Parks for Free