Ironman 70.3 Hawaii. The only Hawaii qualifier for the World Championship, the spring Ironman 70.3 Hawaii triathlon begins with swimming at Hapuna Beach, then moves to biking for 56 miles on Queen Ka'ahumanu Highway, and finishes with a 13-mile run through the Kohala resorts. 808/329–0063. www.ironman703hawaii.com.
Ironman World Championship. Staged annually since 1978, the Ironman World Championship is the granddaddy of all triathlons. For about two weeks in early October, Kailua-Kona takes on the vibe of an Olympic Village as 2,000 top athletes from across the globe and their supporters roam the town, carbo-loading, training, and acclimating in advance of the world's premier swim-bike-run endurance event. The competition starts at Kailua Pier with a 2.4-mile open-water swim, followed by a 112-mile bicycle ride and a 26.2-mile marathon. 808/329–0063. www.ironmanworldchampionship.com.