Extreme Marathons

Ironman Triathlon World Championship, Kailua-Kona, Hawaii
This classic test of stamina combines three endurance events — a 2.4-mile ocean swim, a 112-mile bike ride across the Hawaiian lava desert, and a 26.2-mile marathon along the coast of the Big Island. The current course record is 8 hours 4 minutes and 8 seconds.

• Brett Favre