If you're planning out your summer vacation, make sure to add a few national parks to your itinerary. Every time you share your travels on Instagram, you can increase your chances of winning a VIP trip for two to the national park of your choice.

The National Park Foundation is hosting its "Pic Your Park" sweepstakes now through September 28. To participate, post your selfies from visits to National Park System (NPS) properties on Instagram using the hashtag #PicYourParkContest and a geotag of the location. Making the trek to multiple parks increases your points, with less-visited parks in the system having the highest value. During certain months, the point values of some sites are doubled. You can find a list of participating properties and a schedule of boost periods here.

Following the contest run, the National Park Foundation will decide a winner based on most points earned. The grand prize is a three-day, two-night trip for the winner and a guest to any NPS property within the contiguous U.S. Round-trip airfare and hotel lodging are included. The reward also comes with a 30-day lease of a car from Subaru, the contest's sponsor.

The contest is already underway, with a leader board on the website keeping track of the competition. If you're looking to catch up, this national parks road trip route isn't a bad place to start.