Have you heard? It’s National Park Week! From April 16-24, families across the country receive free admission to any of the 394 national parks in the United States. Although free entry is limited to this week, national parks make great family vacation destinations year-round.

To keep the littlest travelers entertained, the National Park Service offers kids the chance to become Junior Rangers after completing a series of activities at many of the national parks. Once finished, they are sworn in as Junior Rangers and receive a badge and certificate.

Beyond the simple beauty of the great outdoors, many national park activities promote healthy living and one-on-one family time.

Here are five must-see national parks for families:

Acadia National Park (Maine) – Located along the rocky shoreline of Maine, Acadia is the first national park east of the Mississippi River. Acadia is also home to Cadillac Mountain, the tallest mountain on the U.S. Atlantic Coast. Visitors can hike granite peaks, bike along 57 miles of car-free carriage roads and participate in ranger-led boat cruises.

Grand Canyon National Park (Arizona) – It should be no surprise that the Grand Canyon National Park is one of the top must-sees for families– after all, it’s one of the seven wonders of the natural world. The Grand Canyon is truly awe-inspiring at 277 miles long, 18 miles wide and over a mile deep. Beyond the canyon there’s hiking trails, river rafting and camping.

Yellowstone National Park (Wyoming, Montana & Idaho) – Founded in 1872, Yellowstone is America's first national park. The park is best known for its hot springs and geysers, most notably Old Faithful, which erupts every 90 minutes. Camping, hiking and fishing are popular family activities.

Yosemite National Park (California) – Yosemite is one of the most biologically diverse national parks in the country. From its huge rock formations and majestic waterfalls to the ancient sequoia groves, Yosemite is a national treasure. Families can drive through the park, or take advantage of the free shuttle bus system.

Great Smoky Mountains National Park (Tennessee & North Carolina) – With over 9 million visitors a year, Great Smoky Mountains National Park is America’s most visited national park. This is most likely due to its close proximity to the popular neighboring towns of Gatlinburg, Pigeon Forge and Sevierville, Tennessee. Cars are permitted throughout the park and camping, biking, fishing and horseback riding are among the most popular activities. The park is also home to over 1400 black bears—so be on the lookout!