It's the National Park Service's 99th birthday, and everyone's invited to celebrate. Today there's free admission to all 59 of America's national parks. That's 84 million acres open for your hiking, sunbathing and reveling-in-nature pleasure.
These photos from the Department of Interior's Instagram feed will make you want to dust off those hiking boots and start exploring. (Not sure which site to check out first? Here's the complete map of national parks.)