Mariel Galdiano went into Hawaii’s U.S. Women’s Open sectional qualifier "for the experience." The 12-year-old will get the experience of a lifetime.

Galdiano will complete seventh grade at Maryknoll in June and play the most prestigious women’s golf tournament on the planet in July. She birdied the last hole at Poipu Bay last Sunday to win by a shot over University High senior Alice Kim.

Galdiano had no idea what she had done, and still doesn’t.

"She knows it’s a big tournament, but I don’t think she can imagine how big it is until she’s 30 years old or so," her father, Rogelio, says. "Right now she is still in a whirlwind."

She is not the youngest qualifier in the 66-year history of the Women’s Open. Alexis Thompson and Morgan Pressel were 12 when they first played. This year’s Open at The Broadmoor in Colorado Springs, Colo., begins July 7 — 12 days after Galdiano’s 13th birthday.

That makes her the youngest Hawaii qualifier. Honolulu’s Michelle Wie was 13 years, 9 months when she first played in 2003. Wie tied for 39th that year. Hilo’s Kimberly Kim (2006) and Honolulu’s Cyd Okino (2008) were 14 when they first played. Kim also made the cut.

Those are large slippers to fill for a small, soft-spoken Pearl City girl with a penchant for grinning, giggling and spending Sunday afternoons with her buddies at Hickam’s par-27 Ke‘alohi Course.

That has helped her short game immensely. There were other portents of something spectacular.

Galdiano began playing at 5 1⁄2. Her father, a construction foreman, "could tell she was getting bored" when she watched him hit at the range while they waited for mother, Marivic, who works at a bank.

"I got her some short clubs and she started whacking away, whacking away," recalls Rogelio, who now hopes golf will help Mariel afford college. "She was really hitting it."

He enrolled her in Ko Olina’s junior golf program, where she met Allisen Corpuz, another precocious 6-year-old. Galdiano qualified for the Hawaii State Junior Golf Association Tournament of Champions at age 7 and began to work with pro Tommy Hines. Now her father, who tried to soak up each lesson, is her coach. He subscribes to this swing theory: "Why fix it if it’s not broken?"

Last year, Mariel leapt into adult tournaments. She was fifth at the Jennie K. Wilson Invitational and missed out on a place at the U.S. Women’s Amateur Public Links when she lost a playoff. She concluded her breakout summer by taking second at the Hawaii State Women’s Stroke Play and Match Play championships.

At Stroke Play, a 10 on the 17th hole at Mid-Pacific Country Club probably prevented her from replacing Wie as the youngest winner in history. Ten minutes after she finished with a par and a gracious hug for winner Nicole Sakamoto, Galdiano was in tears.

She is nothing if not resilient. Shortly after, she rallied to reach the Match Play final. At this year’s Jennie K., also at Mid-Pac, Galdiano proudly pointed out she played the 17th in 1 under over three days. The dragon was slayed. Six days later, her fearlessness was rewarded with an invitation to join the greatest women golfers in the world.

"It feels like the U.S. Open is all the way at the top," Galdiano says, "and the other tournaments are really down there."

At an Open qualifier so windy that the lone mainland entry averaged 85, the Galdianos went in with the mind-set they were there simply for the experience. "Maybe three, four, five years down the line she can be competitive in this kind of tournament," Rogelio remembers thinking. "That’s why she just stayed loose."

Mariel played her first nine in 4-over 40, didn’t get her first birdie until the 11th hole and shot 78 in her first round — three back of Kim.

"She usually never shoots better than Allisen in high-profile tournaments," Rogelio said. "I told her, ‘Hey, you are one shot better than Allisen.’ I started thinking maybe things are going to change. She started telling me, ‘Dad, don’t forget we are going for the experience. Don’t expect anything.’ That was her big thing. When I start pressuring her, she starts playing bad."

The wind picked up to some 30 mph after lunch, but Galdiano’s game calmed and so did her father. The girl who went into the qualifier with a goal of "not shooting in the 80s" shot 37 on both nines, with three birdies.

Now her game will be tested at The Broadmoor, the longest U.S. Women’s Open course in history (7,047 yards). The USGA is also hoping to break the attendance record of 131,000 set six years ago up the I-25 in Denver.

Michelle Wie and Mariel Galdiano will be in the midst of it all. The much taller one will be in her element. The small one has absolutely nothing to lose.

"I’ll prepare for it the same as the qualifier," Galdiano shrugs. "It’s for the experience."