It was just after dawn on an utterly clear, cool, calm July morning when Karen Zemlin splashed onto Lake Minnetonka's Wayzata Beach. Loons bobbed behind her in the sparkling, 70-degree water as she completed her two-mile morning swim.

"This is really beautiful out here," she said. "But not very good preparation for swimming the channel."

That would be the English Channel — the utterly cold, gray, turbulent and 21-mile-wide waterway between Dover and the French coast at Calais that has lured the world's most ambitious open-water swimmers since the 19th century. Zemlin, 47, of Plymouth, a sunny, focused woman who impresses people around her as a kind of midlife swimming marvel, is booked to dive into that channel sometime between July 29 and Aug. 8. That entry depends on weather, tides and the whims of her escort boat captain and a designated official from the United Kingdom's ruling Channel Swimming and Piloting Federation.

Zemlin's hope is to splash onto the beach in France after a 12- to 14-hour swim — simply, she said, for the "joy of regular people doing something extraordinary."

"I feel good about my training," she said, breaking into a smile. "But if I had to sum all this up in one word, it would be, 'Yikes!' "

Zemlin will join an exclusive club if she is successful (about half of the channel swimmers are these days). Since 1875, when young Englishman Matthew Webb needed 21 hours and 45 minutes to make the first officially documented crossing, just 1,544 people have swum the channel solo. The breakdown: 480 women and 1,064 men (41 of those crossings were round-trip, and three of them completed three legs, ending back in France). Those figures from the federation are current as of last weekend. Seven people (four men and three women) have made the swim this summer in times that ranged from 14 to almost 18 hours.

Zemlin flew last week to England for final training in the channel itself. The adventure that got her there is very much the story of a swimmer and her dad. Roger Bosveld, her 75-year-old father, is a retired St. Paul math teacher, swimming coach, masters swimming pioneer, and lifelong open-water swimmer who still regularly covers a couple of miles in the morning. In June, they swam together in a 2.4-mile race on Gull Lake — she in about 49 minutes; he in about 1 hour, 50 minutes.

"Karen finished first and I finished last," he said. "It was great. We bracketed the field."

Bosveld made the family's first channel swim in 2007, surrendering after five miles in 9-foot seas.

"The [escort] boat captain thought the waves would get smaller, but they got bigger," Bosveld said. "At the crest of the waves I was looking down on the boat. … But I've had my shot and I feel good about it. Now it's Karen's turn."

Daughter and father tell the same story about the defining moment of their swimming lives. Zemlin was 10 and asked her father if she could enter an open-water race. He said no, don't swim.

"I said, 'No, Karen, just go off and have some fun,' " her father recalled. "I knew too much swimming could hurt her. It wasn't her time."

That would come at age 13, the start of Zemlin's competitive swimming life that would take her through high school in Mounds View and the Hamline University team and, finally, open-water swimming — which is defined, basically, as long-distance competitive swimming outside a pool.

A trim 5-foot-6 and 140 pounds, Zemlin is a deliberate and committed athlete. She added 10 pounds this year in preparation for the cold of the channel. In 2000, she set a 20-year series of swimming goals and, she said, "I haven't taken more than a few days off since then." Her real focus came in 2007 when she joined her father for his final, big pre-channel training swim: on a diagonal from Isle to Garrison, on Lake Mille Lacs. It is 22 miles, about the same as the channel, and Zemlin swam it over 10 hours, 2½ hours faster than her dad.

"It was about the coolest thing I'd ever done," she said. "That's when it [the channel swim] started to percolate with me. … But I knew there were some things I needed to learn, some limits I needed to bump into. I needed to see what was really possible."

Swimming season

Minnesota is a mixed blessing as a home base for elite open-water training. Water is not a problem, but it is fresh (most of the storied open-water events are in the ocean) and much of the state's lake water becomes far too pleasant in the summer for anyone who plans to swim, without a wet suit, in a 61-degree English Channel. So Zemlin starts her outdoor swimming season in early May in lakes around the Twin Cities and then migrates north for workouts in lakes with later ice-out dates.

But, ultimately, Lake Superior is the best place for people seeking large, unpleasant places to swim. In June, Zemlin survived what she called a "split channel swim" off Park Point Beach in Duluth. Six hours in the water Saturday, and five hours in the water Sunday. Water temperature? 62 degrees. "Perfect," she said.

Winter is the other trial. There are many laps — in Zemlin's case, 15 to 25 miles of laps each week. She is a member of Hopkins Masters Swim Club. It convenes for one-hour workouts at Hopkins Eisenhower Community Center weekday mornings at 5:30, 6:30 and 7:30. Zemlin swims all three workouts every day, as fresh swimmers change out in the lanes around her, and then she goes to work, teaching autistic children at St. David's Center for Child and family Development in Minnetonka.

"Sometimes, we have 17 workouts in a week, and Karen swims them all," said Scott Tripps of Genesis Aquatics, who coaches the club. "It's inspiring to watch, that's for sure. She's a competitor and a joyful lady; very humble and very easy to cheer for."

As Zemlin's admirers watched in recent years as she swam amazing distances, she never told anyone why. People asked: Just staying in shape … or what? Zemlin said she'd be vague and change the subject.

"I had so much to learn," she said. "I wasn't ready to tell people about it."

In 2013, only her husband, Tom, knew that Zemlin took a course in long-distance swimming off Catalina Island in California. She said she learned important lessons: (a) She needed a strategy to keep saltwater from irritating her mouth (the solution involved a sequence of Advil, Juicy Fruit gum and spitting); (b) you can be colder than what you think is bearable; (c) signs of hypothermia can be confusing for other people to interpret ("Just because I'm slurring my words doesn't always mean I'm in trouble"); and (d) thorough rewarming after a swim is vital.

Also on the sly, Zemlin in 2013 booked her boat captain for the channel crossing, which requires a two-year lead time.

The last two big tests came last summer. First, Zemlin went to New York City and joined the Manhattan Island Marathon Swim, a 28.5-mile slog through the murky waters around parts of New York City. Zemlin's time (7:23:44) was third-best among the year's 47 entrants. (In context, Zemlin's time was less than three minutes behind the time of the UK's Alison Streeter, who has swum across the English Channel a record 43 times, including a round trip and a triple.)

Finally, last August, Zemlin entered the 20-mile Madeline Island Marathon swim in Lake Superior's Apostle Islands. It was supposed to be a relay race. Zemlin entered solo, and won in 8 hours and 49 minutes. ("Truly amazing to watch," race director Scott Armstrong said.)

Said Zemlin: "I was encouraged. Then I could talk about it with people. I had learned so much."

She had learned, for example, that her favorite swimmer's grease (wet suits are forbidden) is a slurry of Vaseline and lanolin, mixed with a hand-held paint mixer; that her best feeding routine is a bland 150-calorie mixture of carbohydrates and electrolytes every 30 minutes, without treats ("I'm kind of all business."); that Lycra suits, which can deteriorate in a chlorinated pool, work best in saltwater; that if she grows her hair out, she stays warmer under her cap; and that she's "very, very lucky" to have so many people help her — monitoring her swims, paddling kayaks, cheering her on.

Now in England, Zemlin said she's trying to stay fresh and in shape, and be ready when her accompanying boat captain tells her: Today you swim. To make sure she hits the beach in France in daylight, Zemlin might be asked to be in the water about 3 a.m. local time. Her husband and her brother, Brian Bosveld, will be on the boat, providing food and encouragement, and recording stroke-counts every half-hour.

"If I'm up around 70 [strokes per minute], I'm good. That's about right for me," Zemlin said. "If I get down close to the 50s, then they'll be looking at me pretty closely."

Did her father have any advice before she left?

"It's like that first time I told her she could swim when she was 13," said Roger Bosveld. "There were about 24 kids in the lake, but I told her, 'Karen, you have a great advantage — you learned how to swim in lakes and you aren't afraid of the weeds! You aren't afraid of the weeds!' She wasn't, and she isn't. And she did great."

Tony Brown is a freelance writer. He lives in Minneapolis.