are most similar to triathlons, with the key difference being the lack of a cycle leg. The bike adds extra complexity for both the athletes and race organisers. Bikes must be transported to the venue, which can be logistically onerous for the athletes, especially for international events. The race director has to select a course that allows space for the bike leg, possibly including road closures. They can be run informally in local lakes. Modern pentathlon is similar to an aquathlon in that both include swimming and running. But swimming and cross-country running are only two of the five events which make up the modern pentathlon, and these are held as distinct, noncontiguous events. Within the pentathlon sport, the term biathle is also used for (training) races comprising swimming and running. These however contain distance stemming from pentathlon races, for instance 200m swimming 3 km running. Another sport derived from triathlon is duathlon, which combines cycling and running but has omitted the swimming part. Events The ITU Aquathlon World Championships have been held annually since 1998. See also Swimrun References External links Swimming Individual sports Multisports Endurance games Athletic sports 20th-century introductions