Eric Byrnes1 of 11
Photo: Jason Wright
Byrnes played 11 years of Major League Baseball for Oakland, Arizona and Seattle. His transition to triathlon wasn't seamless—he admitted that he could barely swim 25 yards when he first considered the sport. But Byrnes, now an MLB Network analyst, persisted and finished 2011 Ironman Arizona in 10:24:31. "It's probably one of the most special things that I've ever done in my life," he told Swim Bike Run Videos after the race.
Tony Kanaan2 of 11
The 2013 Indianapolis 500 winner doubles as a competitive triathlete. He's done numerous Ironman 70.3 races (including Ironman 70.3 Miami three times) and finished the 2011 Ironman World Championships in 12:52:40. Incredibly, he trained for Kona during the IRL season.
Hines Ward3 of 11
The longtime Pittsburgh Steeler had a brilliant NFL career, catching 1,000 passes for 12,083 yards in 14 seasons. Soon after retiring, he set his sights on Kona as part of a "got chocolate milk?" promotional campaign. Ward plans to compete in the 2013 Ironman World Championships, and recently completed Ironman 70.3 Kansas as a tune-up, finishing in 5:53:18.
Mike Richter4 of 11
One of the NHL's biggest stars in the 1990s, Richter played 15 seasons in goal for the New York Rangers, eventually being inducted into the U.S. Hockey Hall of Fame. After his career ended, he took on endurance sports. He finished 2007 Ironman Lake Placid in 12:49:10, and went on to run the New York City Marathon in 3:54 later that year.
Don Davey5 of 11
After playing eight seasons as a defensive tackle for the NFL's Green Bay Packers and Jacksonville Jaguars, Davey started a financial advisory firm and dabbled with triathlon on the side. His multi-sport hobby soon became a passion. Davey has finished four Ironmans (most recently Ironman Germany in 2012) and another 70.3 race, and continues to pursue his goal of qualifying for Kona. "I won't stop until I get there," he said.
Jenson Button6 of 11
The 2009 Formula One World Champion driver has competed in multiple Ironman 70.3 races. Most recently, he placed 78th overall and fifth in his division at Ironman 70.3 California in Oceanside, finishing in a time of 4:29:00. He's also done Ironman 70.3 Philippines.
Jeff Conine7 of 11
"Mr. Marlin" played 17 years of Major League Baseball, mostly for Florida, Kansas City and Baltimore. Almost immediately after retiring, he started training for the 2008 Ironman World Championships, which he received a sponsor's exemption for. He lost 30 pounds and broke his collarbone while training for it. But he finished, in 14:43:35.
Darryl Haley8 of 11
Haley was dubbed the "World's Largest Triathlete" after he finished the 1995 Ironman World Championships in 16:44:15. The former NFL offensive lineman, who played six seasons for New England, Green Bay and Cleveland, was 6-foot-5 and 300 pounds when he raced.
Tyler Wright9 of 11
A 13-year NHL veteran, Wright hung up the skates in 2007 and soon after put on a tri suit. Wright took on the 140.6-mile challenge to raise money to help fight pediatric cancer. He succeeded, too, finishing the 2010 Ironman Canada in 12:29:59. He now works in the front office of the Columbus Blue Jackets.
Sean Green10 of 11
After playing three seasons in the NBA for Indiana, Philadelphia and Utah, Green had a lengthy basketball career overseas before turning his attention to training and coaching. That included starting his own triathlon team and becoming a USA Triathlon-certified coach. Among his own multi-sport accomplishments was a finish at Ironman 70.3 Rhode Island in 2009.