In addition to the usual gear—water bottle, hiking boots, freeze-dried food, rain gear, binoculars—needed for an excursion to one of our country’s 423 national park sites, visitors will now need to stash at least one more essential item in their backpacks: A mask.

That’s because the National Park Service this week implemented a mask requirement for employees, visitors, partners, and contractors in all park facilities and wherever physical distancing can’t be maintained outside, such as on busy trails and in popular viewing spots.

In other words, what you’ve been wearing on your weekly trips to Safeway for the past year is now required for your once-in-a-lifetime vacation to Sequoia this summer.

The newly enacted rule comes as a direct result of a recent executive order from President Biden. Additional health measures have also been put into place across the service, from “capacity limits to one-way trails, or even temporary closures in response to local conditions,” according to a statement released yesterday.

“Wearing a mask around others, physical distancing, and washing your hands are the simplest and most effective public health measures to help stop the spread of Covid-19,” said Captain Sara Newman, director of the NPS Office of Public Health. “Getting outside and enjoying our public lands is essential to improving mental and physical health, but we all need to work together to recreate responsibly.”

“Working with public health officials and following the latest science and guidance, we can make national parks safer for employees, visitors, and partners,” added NPS Deputy Director Shawn Benge. “We will continue to evaluate operations and make appropriate modifications to visitor services as needed.”