By Dana Kozlov

(CBS) – Ready, set, plunge. A beach full of people will again dive into Lake Michigan to raise money for Special Olympics this Sunday.

Among them will be hundreds of high school athletes, recruited by a South Side alderman.

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But one student is doing it for a very personal reason, CBS 2’s Dana Kozlov reports.

Fifteen-year-old Hugh Devane makes a splash almost every day on Mount Carmel High School’s water polo and swim teams. This weekend, he’s about to take an entirely different plunge.

Of the polar kind.

Devane and dozens of his fellow athletes will be jumping in to raise money for the Special Olympics.

More than 200 athletes from four other South Side high schools will join them. The idea is from 19th Ward Ald. Matt O’Shea, a longtime polar plunger himself. He says it’s about “athletes supporting athletes.”

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But it’s more than that for Devane, a junior.

His 7-year-old sister Dorothy, who has Down syndrome, is his real inspiration.

“Every moment I’m with her, she’s just like a ball of joy,” he says.

Like him, she’s a budding swimmer. She takes swim lessons through Mount Greenwood Park’s special recreation program.

Marist McAauley, St. Rita and St. Ignatius are the other schools taking part.

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The athletes are expected to raise more than $40,000 for the cause.