"It's all about fun," Bobby said before the race, adding that he was, of course, hoping to beat his younger brother (he did, by 24 minutes).
There was Sarah Reinertsen, 38, of San Juan Capistrano, Calif., who was competing on a prosthetic left leg. Her leg was amputated when she was a child.
Reinertsen's relay, which featured another amputee, finished in just over two and a half hours, less time than it took to get to many Shore points on Friday.
"You have to use what you've got in life," she said while warming up, explaining that she has different prosthetics for running and cycling.
And there was Max Fennell, 25, of King of Prussia, a former soccer player and self-coached competitor, who is striving to become one of the only African American triathletes to turn professional. Fennell came across the end line in two hours and nine minutes, crumbling to the ground after finishing but able to get back on his feet and walk away.
"Obviously, I'd love to win, but if I'm doing better every single race, that's big for me," Fennell said afterward, dripping sweat.
Nearly 2,000 others competed Sunday, according to Molly Quinn, vice president of the Competitor Group, which organized the race. About 1,200 competed in a shorter triathlon along the same route Saturday, she added.
And Sunday morning, as a Rolling Stones cover band blared in the background to help Olympic course finishers celebrate, Quinn said she thought the event had gone very well, without major injuries or security issues.
"I really feel like everything came together," she said, adding that the only unforeseen change was having to provide water and ice for the running portion Sunday as the weather heated up.
Given the grueling nature of a triathlon - the Olympic course was 1,500 meters of swimming in the Schuylkill, 24.8 miles of biking around Fairmount Park, and 6.2 miles of running along Martin Luther King Jr. Drive - safety is no guarantee.
In the 2010 Philadelphia Triathlon along the same route, Derek "Rudy" Valentino, 40, died while swimming in the Schuylkill. His body wasn't found for about 34 hours.
Additionally, there were 45 deaths in triathlons nationwide between 2003 and 2011, according to a study by USA Triathlo; 30 of them were in the water.
But on Sunday, as the finishers were trickling across the line, most were simply enjoying the sunny weather and reveling in their accomplishment.
Around 10 a.m., Pat Carey, 23, of Fairmount, was even thinking about enjoying the complimentary beer afforded to finishers.
"It's going to hit my mouth and vaporize," he said with a laugh.
Contact Chris Palmer, 609-217-8305, firstname.lastname@example.org, or follow on Twitter @cs_palmer.