WASHINGTON (CBSDC) - Thousands of triathletes are set to converge on D.C. Sunday morning to participate in The Nation’s Triathlon.

The annual event consists of a 1.5 kilometer swim in the Potomac River followed by a 40 kilometer bike ride throught the heart of the District and it finishes with a 10 kilometer run past the monuments. With 5,000 entrants, it’s the largest international-distance triathlon in the country.

Credit: WNEW reporter Kevin Patrick

Veteran triathletes say you don’t have to be an elite-level competitor to enjoy the sport. For some it’s a means to enjoy the outdoors. Others say the three disciplines — swim, bike, run — helps keep training and racing interesting. Still others say the sport provides a source of stress relief from the day-to-day routines.

Triathlon has exploded in growth since 2000.

USA Triathlon, which is the governing body of the sport, reports its membership has increased from approximately 22,000 in the year 2000 to more than 150,000 members today.

Credit: WNEW reporter Kevin Patrick

In the past two years the swim portion of The Nation’s Triathlon had to be cancelled due to high levels of bacteria in the Potomac River due to rain. Testing was done on the waterway late in the week and race organizers were given the go-ahead to conduct the swim as scheduled.