OKLAHOMA CITY — They marched nude by the hundreds through forests, by lakes and along mountain trails, with many hoping to go unnoticed.

For the most part, national Hike Naked Day went according to plan last Sunday, though there were a few surprised people on the trails who came across hikers wearing as much clothing as the surrounding trees.

National Hike Naked Day is celebrated on the first day of summer and likely started on the Appalachian Trail, its backers said. It is one of the many offshoots of the nudist lifestyle that include skydiving, cycling and whitewater rafting.

For its participants, it is also the most natural.

“Any hiking feeds the soul, but nude hiking frees the soul,” said Steve Bosbach, 66, who led a group of hikers on the Pacific Crest Trail in Oregon to celebrate.

Bosbach started a naked hiking social group earlier this year and now has 26 members who like to take it off and take to the trails.

“Here in Oregon, we have fantastic hiking opportunities, and the state has a very liberal policy on nudity,” he said.

The hikers often find each other through social media to plan their outings, with many devising strategies to avoid public notice on public lands.

Advice is abundant for first timers: Hiking shoes do not violate the spirit of the event, apply sunscreen frequently and liberally to places not often exposed to light, chafing is common with backpacks and ticks are easier to spot with the less you have on your body.

Beverly Price, president of the American Association for Nude Recreation, is a long-time nude hiker and has led numerous multiday nude excursions, including camping and rafting in the Grand Canyon and the Utah Canyon Lands.

At 71, the Phoenix native says traditional hikers usually have no problem with naked hikers as long as they are not surprised.

“I find if you warn people ahead of time, they don’t mind,” Price said.

“In fact, most of them are jealous. They want to try it, but their spouse doesn’t want to, or they are afraid their parents will disapprove or, heaven forbid, the kids might find out.”

Nude hiking laws and acceptance varies from state to state. In Oregon, nude hiking is not prosecuted on the U.S. Bureau of Land Management lands, naked hiking groups said.

But Arkansas is one of the most restrictive jurisdictions for nudity, they said. Any exposure technically is illegal to anyone other than a doctor, nurse or spouse.

In states like Oklahoma, however, nude recreation is confined to naturist resorts and private lands. Yet Hike Naked Day came and went at Oklahoma’s Oaklake Trails Naturist Park without any of its members noticing.

Dennis Duncan, office manager at Oaklake, said the naturist resort’s 5-mile hiking trail is filled every day with naked hikers.

“The majority of us are naked the majority of the time, so days like that aren’t a big deal,” Duncan said.

“We swim and hike naked all the time. Every day is Hike Naked Day.”