This Saturday marks the start of National Park Week, and the National Park Service is throwing a party to celebrate. Entrance fees for all National Parks are being waived — that’s right, you can visit any National Park for free on Saturday, April 21.

There are four free days at National Park Service sites each year, but the National Park Week kickoff is perhaps most jovial. Think of it as a sort of unofficial kickoff to road trip season. The NPS partners with the official charity of the National Parks, the National Park Foundation, each year to offer a packed schedule with a variety of happenings to celebrate the week and get people stoked to visit and support the parks throughout the summer.

Guided hikes and presentations are part of the plan at many parks across the country. To go along with the official theme of “Park Stars,” the Foundation plans to highlight the rockstar guides that lead guided hikes and knowledge shares. They also encourage visitors to hang out past dark and gaze up at the stars.

The NPS and the Foundation are “highlighting stories, experiences, and sites that brighten the National Park System,” according to a statement on the National Park Foundation website. Many parks will also celebrate Earth Day on Sunday, April 22, including a family-friendly festival at Yosemite National Park.

Heading to one of the parks this weekend? Check out the list of events here. Join the conversation by using #findyourpark on social media. If you miss Saturday, there are two more free days later in the year: National Public Lands Day on September 22 and Veteran’s Day on November 11.