A naked event is set to take place on the Colorado slopes ... one where the ladies and non-binary skiers are allowed to shred the mountain in just a pair of boots!

Boot Tan Fest is bringing back its annual retreat in March at CO's Sunlight Mountain Resort -- the program is open to those who are non-binary and "female-identifying," and is expected to bring in around 500 people this year.

The event kicks off after the resort closes at 3 PM, but folks attending can enjoy the facilities when it's open to the public during the day ... with their clothes on, of course.

The event first popped up in 2021 with less than 30 participants ... but has certainly garnered a big audience as time went on -- and this year, ticket holders will have access to women-owned brands, a tattoo booth, camping, and live entertainment.

Jenny Verrochi, founder of Boot Tan Fest, said the fun in the snow is all about putting up a welcoming environment ... saying, "Come by yourself and you’re sure to walk away with friends."

BTW, going fully nude isn't a mandate for this thing ... but seeing how popular this ski event is, it looks like you'd be in the minority if ya don't strip it off.