A wet Danskin Triathlon in Fairmount Park

For months, Rosemary Tomkus had worried about swimming a half-mile in the Schuylkill during the Danskin Triathlon in Fairmount Park yesterday.

But when a severe thunderstorm cancelled the swimming leg of the race, Tomkus was more disappointed than relieved.

"I really felt ready to do this today. The nerves had subsided," Tomkus, 52, of Gilbertsville, said, putting aside her wet suit and getting ready to join about 2,500 other women in the annual endurance test.

For a brief time, the rain let up and the racers, most of them anyway, got to finish the event, with an extra 5K run substituted for the swim. But many got caught in a second downpour at the tail end of the race.

"It was pretty scary. I have raced in storms but never in a situation with thunder and lightning," said Rebeccah Wassner, 34, a pro athlete from New York who won the race in 1 hour, 9 minutes, 5 seconds. Her twin sister, Laurel, came in second.

The Danskin is a sprint-distance triathlon combining a half-mile swim, a 12.4-mile bike ride and a 5K, or 3.1-mile, run. The race brings out many groups and first-timers who perhaps hope just to get through the day rather than set time records.

Racers in the gruelling Ironman, by comparison, swim 2.4 miles, bike 112 miles, and run a marathon, 26.3 miles.

"I already gave the ambulance my medical card," joked Sheila Doherty, 34, of West Chester, who was competing with seven friends in their second triathlon. For their first, in Miami, they weren't timed, so "we're stepping it up," she said.

Four years ago, Tomkus was a wife, mother, and an employee at Globus Medical, but not an athlete. Then friends asked her to go for a 25-mile bike ride and she liked it so much she bought an $800 bike.

Now she bikes all the time and has done several long-distance rides, including the MS 150 and Bike Philly. But after hearing about the Danskin Triathlon last year, she decided she needed a new challenge.

"I went from doing nothing to four years later doing a triathlon," she said.

As impressive as that is, Roberta Leventhal has her beat. The 58-year-old lawyer from Roslyn, N.Y., learned to swim just last year and has already done four triathlons - one of them an Olympic-level course that is double the distance of the sprint.

"It's the best thing I've ever done. It's changed my whole life," said Leventhal, who was waiting for the race to start with her training team, First Wave Tri, and sister, Carol Albert, 63.

Albert, a former physical education teacher from Orlando, Fla., entered her first triathlon four years ago. Both women had run half-marathons but decided triathlons were easier on their bodies.

Leventhal has now qualified for nationals in her age group. She gives all the credit to her coach, Kerry Simmons, who was there to cheer on the team.

For those without their own coaches, Danskin provides mentors to guide the uninitiated.

Tomkus' mentor, Trish Bryon, 48, a lawyer at Globus, has worked with 28 women since the spring to bring them up to speed. She prepares a training schedule, stays in touch via phone and e-mail, and recently took them to Blue Marsh Lake near Reading so they could take a dip in open water.

"They've been in a pool where it's nice and clear. They can get in dark water and freak out. There are no lanes or sides to hang onto," she said, though during the race they can grab onto roaming kayaks if they need a breather.

Bryon entered her first triathlon eight years ago while on vacation on Key Biscayne, Fla. She led the pack of first-timers, inspiring her to start seriously training when she went home.

Since then, she's done 50 races, including three Ironman events.

Mentoring is almost as thrilling as being in a race, she said.

"Watching these women crossing the finish line and seeing the looks on their faces," she said, "it gives you chills."

Tomkus, who crossed the finish line before the soaking rain, was elated to make it to the end.

"What a day. I finished. I did it," she said, after meeting up with her proud husband and two children. "Even though we didn't swim, there was so much rain I still say I did a triathlon."