In honor of the National Park Service’s 99th anniversary, entrance fees for all parks under the National Park Service’s protection will be waived on Tuesday, Aug. 25.

Acadia National Park is among 130 national parks — out of 400 — that require an entrance fee. Even though the fee to explore Acadia isn’t too expensive to begin with — private vehicles carrying fewer than 16 passengers are only $25 and the pass is valid for seven days — this free entrance day is a pretty good reason to explore the park.

Free days are usually crowded, but because the date lands on a Tuesday this year, the park shouldn’t be too overwhelmed.

To celebrate the history behind the 99 years of the National Park Service, here’s some Acadia history you can take with you when you visit this August.