Duathlon is a great sport for people looking to move into multi-sport races. For those not quite ready to take on a triathlon just yet, or for athletes wanting to avoid open water swims through the chilly winters, this is the perfect inbetween. It's a two-sport race which combines cycling and running in three stages (run-bike-run). Typically, the last run is half the distance of the first, so a sprint distance will be 5km-20km-2.5km and a standard distance will be 10km-40km-5km.
But don't be fooled, just because there's no swim, this doesn't mean it's easier than a triathlon. A lot of athletes will tell you a duathlon may actually be harder.