SEA ISLE CITY — Cassidy McClain was shivering and her teeth were chattering as she awaited the start of the finals at the Open Shortboard of the Eastern Surfing Association’s Northeast Regional on Sunday.

Yet when it came time to charge into the ocean at the 40th Street beach, the 17-year-old Ventnor resident and Atlantic City High School senior was the only one of the six surfers not wearing neoprene boots with her wetsuit.

McClain’s fashion choice helped her make history.

She wowed the crowd and the judges with her aggressive style during the 20-minute session and became the first female competitor to win an Open Division at an ESA regional event. The ESA bills itself as is the world’s largest amateur surfing organization, stretching from Florida to Maine and including the Gulf Coast and Great Lakes.

“What she just did is mind-blowing,” said Lisa Roselli, co-director of the ESA’s host South Jersey District. “You’re talking about the best surfers in the entire region competing against each other.”

Northeast Region director Lester Priday said the Open Division was created about 10 years ago to determine the best surfer at a meet, regardless of age. For instance, McClain surfed against guys ranging in age from 11 to 48.

Anyone at the meet is eligible to enter. Surfers advance through a series of qualifying heats held throughout the weekend to reach the final. McClain was the only female to enter and won two earlier heats against a total of 10 males.

“It’s basically for bragging rights,” Priday said. “It gives people of all ages a chance to compete against each other.

“We may have had one girl make the finals before, but Cassidy is definitely the first one to win it. It’s incredible.”

McClain, who earlier won the Junior Women’s Division, had modest expectations when the final began.

She originally had set a goal to reach the final and then was hoping to place among the top three.

But she took advantage of her local knowledge — she sometimes surfs at 40th Street Beach — to take control. Surfers are required to catch at least two waves in order to receive a total score. Cassidy, who is sponsored by Billabong and rides for Heritage Surf and Sport, stuck to the outside and wound up grabbing eight.

“It was really fun out there,” she said. “(The conditions) look horrible from the beach, but once I got out there, it was much better. Most of the waves were chest-high, about 4 feet.”

She saved her best ride for the end of the competition. With about two minutes remaining, she caught a left and executed two sharp turns that produced cheers and cries of “fierce” from the crowd.

The judges agreed, giving her a score of 9.0 on a 10-point scale. It was the second-highest score of the entire, three-day event and prompted officials to give her a “Hot Wave” award.

“I just tried to stay aggressive,” McClain said. “I tried to go for the most critical maneuvers — verticals and power turns — on every wave, and it worked. I can’t believe I beat all those guys. I’m so stoked.”

The Open Shortboard was the final event of a three-day meet that featured more than 200 surfers in 25 divisions. The top three finishers in each division received automatic spots in the ESA’s Eastern Surfing Championships, scheduled for Sept. 15-21 in Nags Head, N.C.

Cassidy earned her place by winning the Junior Women’s Division earlier Sunday. She finished third at Nags Head last year.

Several other local surfers, including 11-year-old North Cape May resident Kyle Tester, will join her.

Tester, a fifth-grade student at Charles W. Sandman Consolidated School in Lower Township, placed second in the Boys Menehune (11 and under) Division and landed a spot in the Open Shortboard final, where he finished sixth.

“I started pushing him into the water when he was about 3 years old and he’s been surfing ever since,” Tester’s father, Scott, said. “I surf, too, so it’s something we can do together. We’ve wound up traveling quite a bit. Kyle was in a competition in Newport Beach, Calif, last week, and we’ve also been to Mexico, Hawaii and Puerto Rico this year.”

The Northeast Regionals were held in the area for the first time since 2001, when they were also in Sea Isle City.

The contest was supposed to be in Belmar this weekend but had to be moved due to damage from Hurricane Sandy. When ESA officials were searching for a new site, Roselli and South Jersey District co-director Joe Grottola offered to host it.

“This is my first time at the Northeast Regional and it surpassed my expectations,” ESA executive director Michelle Sommers said. “The talent was tremendous and everyone here was just so nice. Lisa (Roselli), Joe (Grottola) and the entire South Jersey District really stepped up, as did Sea Isle City. The locals were so supportive and very welcoming. We had a great time.”

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