The water temperature was only 39 degrees, but close to 400 participants braved the cold to dive in.
One group from Ruth Barker Middle School in Bentonville has done the plunge every year. Special education teacher Suzy Hubbard said the group always chooses a theme for their costumes and this year it was Snoopy and the Peanuts.
"We take it pretty serious," Hubbard said. "We started this in July, deciding what we were going to be."
All the proceeds raised goes towards training and holding competitions for Arkansas Special Olympic athletes. Speech therapist Brie Norton said the cause hits close to home.
"We have two classrooms with kids with intellectual disabilities that get to benefit from the program, so it's a cause really close to the heart and we're very passionate about it."
Norton said after doing the plunge several years in a row, she does have some advice to first-time plungers.
"Layers are not your friend because you can't get them off quickly," Norton said. "So some people layer up, but I think they'll learn that it's not as easy to get those clothes off."
Organizers said the polar plunge at Beaver Lake is the largest plunge in the state.