Memorial Day Weekend is the unofficial start of summer – and with it, the beckoning of warmer weather and the great outdoors – and in the upcoming months, there’s a slew of ways to do just that at national parks across the country. Since there are parks in four U.S. territories and every state except Delaware, chances are there’s one within easy distance for you, and entry fees are usually no more than $20 per car.

Here, some of the best offerings guaranteed to inspire you to lace up the hiking boots and get outside. Some highlights: a full moon hike this weekend and the fourth annual National Get Outdoors Day on June 9, which comes with free entry into many popular parks, including Grand Canyon National Park and state parks across the country.

Celebrate the longest days of the year with a nearly month-long itinerary of activities at Indiana Dunes National Lakeshore. The events kick off this weekend with two ranger-guided activities, including a nighttime hike under the full moon on June 3. In addition, there are four dates when participants can watch an archeological dig performed by the NPS and the University of Notre Dame and learn about some of the 10,000 years of human habitation in the lake’s dunes.

For National Get Outdoors Day on June 9 – which supports the  inspiring Let's Move Campaign by First Lady Michelle Obama – numerous national and state parks are offering free admission, as well as great family-friendly activities. Among them: an interactive T-Rex exhibit at the Field Station: Dinosaurs recreation area in New Jersey and huge outdoors festival, with free shuttle service, at the Get Outdoors Colorado event in Denver.

Further into the fall, be sure to mark your calendar for additional free entry days into the country's national parks: September 29 in honor of National Public Lands Day and November 10-12 in celebration of Veteran’s Day.

In other NPS news, nearly 1,400 miles of trails were added to the National Trails System, Secretary of the Interior Ken Salazar and NPS Director Jonathan Jarvis announced on Thursday.

Finally, the outdoor paradise of Park City, Utah, is offering a free three-night trip, plus airfare, to the winner of what seems like a pretty easy contest, the Park City Great Getaway. You simply register, drag and drop photos of your dream Park City itinerary, and that's it. The contest is open through August 14, and you can even opt out of the email newsletter.

To start planning your next trip, see our Sports & Adventure Travel Deals.