The length of the swimming portion of a triathlon depends on the age level and competitiveness of the race. The standard, or Olympic, swim distance is 1,500 meters, or slightly less than a mile. But there are many other popular triathlon formats -- sprint, team relay, long distance and ultra long distance (Ironman) -- each with its own swimming distance rules. The Ironman swim portion is a lung-busting 2.4 miles (3.8 meters) long.
Contrary to popular belief, there is no rule about what stroke you must use in the swimming portion of a triathlon [source: ITU]. Just about everybody opts for the classic freestyle, but you won't get kicked out of an Olympic triathlon for doing the doggy paddle. You can rest during any part of the swim leg by either standing on the bottom or holding onto a floating buoy. This rule helps prevent injuries or even death: Of the rare fatalities during triathlons, almost all of them occur during the swimming section [source: WISN].
The most controversial rules for the swimming portion of a triathlon concern the use of wet suits. Wet suits were originally used by triathletes only in cold, open-water races. Then athletes began to notice a welcome side effect of staying warm in the water: speed [source: Kent]. Wet suits are designed to trap a thin layer of water next to the body. That water is heated by the body's natural temperature, creating a warm protective barrier against the cold. As triathletes soon discovered, this trapped layer of water also increases the racer's buoyancy in the water. The less energy you expend trying to stay afloat, the more you can apply to pushing forward. Once the word got out, triathletes started using wet suits in all water temperatures, not just the frigid San Francisco Bay.
In response, the International Triathlon Union (ITU) came out with water temperature limits restricting the use of a wet suit. According to the ITU rules for competitive races, all triathletes must wear a wet suit in water temperatures under 14 degrees Celsius (57 degrees Fahrenheit) and have the choice of wearing a wet suit up to 20 degrees Celsius (68 degrees Fahrenheit). Under ITU rules, wet suits are forbidden above 20 degrees Celsius (except for long distance races, where the limit is raised to 22 degrees Celsius, or 72 degrees Fahrenheit) [source: ITU]. In addition, the ITU restricts the thickness of wet suit material to no greater than 5 millimeters (0.2 inches). USA Triathlon recently announced that it will adopt the same rule by 2013.
Now, let's talk about the biking leg of the triathlon. Don't forget your helmet!