They've been doing it for 7 years. This year they met at Kickapoo State Park.
The group says all you need are 4-season tents, thick sleeping bags and a camp fire.
"It's about adventure. It's about having fun. It is a little crazy. I'll admit it's a little crazy, but we have a good time," camper Bonnie Wyatt said.
The extreme campers will be freezing their butts off until Sunday afternoon. That's when they're packing up for the weekend.