She rarely wears a watch, always has her cellphone nearby.

You want her, you text her, her mother sagely advises.

Renee Brock/Special to AJC (ENLARGE)

Marist swimmer Kathleen Hersey, who won four gold medals in the 2007 Pan American games, heads to the Olympics.

Photos: Georgians in the Games

When 18-year-old U.S. Olympic swimmer Kathleen Hersey finally does call back for an old-fashioned telephone interview after a few days of missed connections, it's 15 minutes later than the absolute latest you'd been told to expect her.

And absolutely worth the wait.

"The [Olympic] trials was an emotionally exhausting experience," Hersey half-moans in one breath before sounding practically beside herself with happiness in the next. "To go through it again with an even bigger meet will be absolutely thrilling!"

Clearly, this Roswell-reared Marist High grad is a totally typical teenager. Except for how she's totally not.

For most kids, the summer between high school and college is all about deciding on a major (then deciding on a different one), mentally decorating the dorm room and getting one's fake ID in proper working order. But if Hersey has to write a "How I Spent My Summer Vacation," essay when she starts the University of Texas later this month, she's got an A+ opening line: "Took on the whole world."

"The Olympics is all about representing your country," Hersey says from Palo Alto, Calif., where she's training to swim the gracefully grueling 200-meter butterfly in Beijing. "It's not just about you and your family anymore."

That's heady, heavy stuff for a young woman who, just a few months earlier, had been deciding whether or not to join the kids locked inside Marist for some traditional graduation night revelry. A young woman who, by the very nature of who she is and what she does, is in a never-ending power struggle with time.

Hersey is the third-youngest member of a 44-person squad with a history of going into the Olympics and letting everyone know who the real aquatic grown-ups are. In Athens in 2004, Americans won 12 of 32 events and nearly one-third of all the swimming medals. At the U.S. team trials in Omaha, Neb., last month, nine world records were set — three more than four years ago.

That Hersey understood the enormity — and incredible opportunity — of the moment at the trials became clear to her longtime coach in the hours before the 200 fly final.

"She was the first one in the van [going] to the pool, and that has never happened," says SwimAtlanta's Mark Minier. His prize pupil "tends to" run late on dry land, he says. "Usually, the girl still looking for her credential and bathing suit is the Kathleen I know. I wanted to say, 'Where is Kathleen Hersey?!' "

It's tempting to respond: Exactly where she's supposed to be.

Elation and realization

The quadruple gold medalist at last summer's Pan American Games posted the fastest 200-meter fly time in the world earlier this year, although her ranking has since slipped to No. 10. Still, Swimming.com ranked Texas's incoming recruiting class — "headed by Kathleen Hersey" — No. 1 in the country.

So when she finally plunges into Beijing's "Water Cube" (more formally, the National Aquatic Center) once the swimming competition starts Saturday, it may be that she's simply reached her most logical destination.

"We all agreed when we met early on that this was about going the distance," says Marist coach Terry Blish, whose teams Hersey helped power to state titles the past two years. "It was, 'It's not a question of if she goes to Beijing. It's when she goes.' "

But logic doesn't always figure in the world of elite swimming, let alone the world of teenagers. While Hersey managed to navigate all the usual emotional and logistical whirls of senior year — making five consecutive weekend recruiting visits to different colleges; saying yes to the prom, but no to the after-party — her intense training schedule only started with about 30 hours of pool time each week. To her financial consultant father, Brian, 58, it was "like doing a full-time job."

In Omaha, 101 women were entered in the 200 fly, knowing that finishing third was arguably worse than coming in 101st: Only the top two in each event would qualify for the U.S. team. So in the final, when Hersey went out extremely fast, seemed to fade slightly and then somehow kicked it into overdrive to touch the wall second, her smile was so genuinely wide, the TV cameras couldn't help but find her.

The cameras, though, couldn't tell the whole story.

"It's kind of weird. When I made the team, it was the most elated I ever felt about my swimming," Hersey recalled. "But at the same time, it was, 'This was it. This part of my life is over.' "

That's not teenage melodrama talking. Quite the opposite, in fact. She knew she'd be away at training camp when her parents made a long-scheduled move to South Carolina, meaning she'd never be going back to the family home in Georgia. Or to the time when she was an adolescent learning to make very grown-up decisions in hopes of someday, maybe, becoming an Olympian.

In her father's wake

"We put that ball in her court when she was in the seventh or eighth grade," says Regina Hersey, 62, a freelance book editor.

In Roswell a few days before the big move, she's surrounded by packing boxes and memories of her only child having to decide if a giddy sleepover one night was worth the pain in the pool the next morning. "I said, 'You're in charge of your own existence. You have to start making your own decisions on these things.' "

Not every decision, her parents suggest, has been an outright winner. But others, like looking to her father's life for inspiration in her own, have been pure gold.

Brian Hersey has needed a wheelchair to get around since developing a spinal cord problem more than 20 years ago. But one only needs to hear the story of him "fanny-bumping" his way up the stairs in a quaint old Irish B&B to understand that it's never held him back, professionally or personally.

"My dad has always overcome so many obstacles, it makes you feel there's nothing you can't do," says Kathleen. "There isn't anything you can't not try to do."

Indeed, Brian likes to swim, so it only made sense that he and Regina would enroll the daughter they'd adopted as a newborn in swimming lessons at age 2. Two years later, she raced for the first time. An older niece summering with the Herseys was on the neighborhood swim team and little Kathleen wanted to do what the older kids were doing. She swam the 25-yard freestyle well, but really seemed to come alive during the backstroke, when she could see the crowd smiling and waving the whole time.

"The next week, her freestyle race was horrendous," Regina Hersey chuckled. "She was picking her head up out of the water with every stroke and smiling at everyone."

Many, many miles in the pool later, Kathleen sums up swimming's appeal as "just the challenge of getting from one end to the other first, fastest, when we're not even really supposed to be in the water."

Right on schedule?

Thinking deep thoughts like that can be an occupational hazard of having your head underwater for long stretches; so can swimming's tendency to make you see everything through the prism of time.

"I wore a watch to class a few times and I would be saying to myself, 'On the :30 we should be doing this,' like I was at practice," Hersey sighs. "You become obsessive-compulsive, and it takes over your life."

So she's largely lost the watch and, more than occasionally, loses track of time, whether it's an appointment for a newspaper interview or the start time of her next practice (she's off by two hours, her roommate has to inform her).

Better she should listen to her inner clock, anyway, the one that keeps her zeroed in on what's truly important. She's gunning for a medal in Beijing, but if it doesn't happen it won't be the end of the world — or for lack of trying. Only a few days earlier, she'd learned that her fellow Atlanta Olympian, Eric Shanteau, would be competing in Beijing despite having been diagnosed with testicular cancer.

"My dad and Eric kind of represent what swimming is about, which is perseverance," says Hersey. "It's also about racing and loving what you do, but you mostly have to have the heart of a champion. They both embody what we should want to do with our swimming here."

Sounds like she's exactly where she's supposed to be.