Again this year, Minnesota’s 75 state parks and recreation areas have free admission Friday to encourage time outdoors on a day — Black Friday — many reserve as a post-Thanksgiving day of shopping madness.

The effort dovetails with the #OptOutside campaign by REI, which began closing its doors on Black Fridays in 2015 to push back against consumerism and allow its employees a day off with nature.

The outdoors retailer, in fact, has upped the initiative this year with another call — Opt to Act — encouraging the public to spend time being good stewards and cleaning up natural areas.

There are three related events planned in Minnesota, two in the metro and one in Center City:

• Fiwygin Outdoors (“Fit in Where You Get In”) will host a cleanup at 11 a.m. Friday at Como Lake in St. Paul. Meet at the lake pavilion. (Details online at bit.ly/comoclean.)

• St. Croix River Association will host its Trot Off the Turkey Hike from 1-3 p.m. Friday through Wild River State Park in Center City. Meet at the park visitor center. Participants will hike and pick up trash as they go. (Details at bit.ly/croixclean.)

• Chapters of two groups, Native Women’s Wilderness and Women Who Hike, will host a morning hike and cleanup at 10 a.m. Saturday at Minnehaha Creek. Meet on the south side of Sea Salt eatery next to the falls. (Details at bit.ly/minneclean.)

Share the day on social media with #FreeParkFriday, #OnlyinMN and/or #OptOutside.

Here are some other ways to get out at Minnesota state parks and natural areas:

Hike it off

Whitewater State Park

10-11 a.m. Friday

• Walk off Thanksgiving’s meal during a hike into a valley for signs of wild turkeys. (1-507-312-2300; mndnr.gov/whitewater)

Story time

Lake Bemidji State Park

1-2 p.m. Friday

• Bring the children for a nature-based story and craft-making. (651-343-8324; mndnr.gov/lakebemidji)

Post-holiday hike

Interstate State Park

1-2 p.m. Friday

• Participate in a mile walk. Meet at the Taylors Falls Community Center. It’s also the weekend of the Taylors Falls Lighting Festival. (651-465-5711; mndnr.gov/interstate)

Wildlife homes

Fort Snelling State Park

1-2 p.m. Saturday

• Search with a naturalist for the park’s vacant wildlife homes. (612-725-2724; mndnr.gov/fortsnelling)

Adventure mystery

Lowry Nature Center

1-4 p.m. Friday

• Instead of a Black Friday buying spree, try an adventure hike with your family. Try geocaching, visit parts of the park you may not have seen before, and uncover clues to solve a nature mystery. Ages 17 years and younger must be accompanied by an adult. (763-694-7650, bit.ly/lowmystery)

A hike for women

Eastman Nature Center

7-9 p.m. Saturday

• Wind down after the holiday with friends and make new ones, too. Search for nocturnal animals on a nighttime hike with a naturalist. Then socialize around a bonfire. Reservations required. (763-694-7700, bit.ly/threehike)