A visit to one of America’s highest-regarded natural treasures is one way to celebrate Earth Day. Even better: You can do it while saving money.

Earth Day is April 22, which happens to coincide with the start of National Park Week. It’s one of the few days on the year when the National Park Service waives entrance fees to its lands, including some of Colorado’s most iconic destinations.

The state has four national parks: Rocky Mountain, Great Sand Dunes, Black Canyon of the Gunnison and Mesa Verde. Those represent a range of experiences, from the high alpine outside Estes Park, to North America’s highest sand dunes in the San Luis Valley, to the steep and deep canyon in western Colorado, to the ancient dwellings in cliffs farther south.

Those entrance fees are typically $25-$30 per vehicle. Reservations for Rocky Mountain National Park aren’t required again until May 26.

Several designated monuments will be free of charge that Saturday as well. That includes Florissant Fossil Beds west of Colorado Springs; Bent’s Old Fort outside La Junta; and Colorado and Dinosaur national monuments on the Western Slope.

The National Park Service’s next free day will be Aug. 4 in celebration of the Great American Outdoors Act.