Which sport combines swimming, cycling, and running?

The sport that combines swimming, cycling, and running is triathlon.

A triathlon consists of three consecutive disciplines, normally in that order: a swim, a bicycle ride, and a run. The clock usually continues during the transitions, so athletes must change equipment quickly as well as perform well in each sport. The transition areas are often called T1, between swimming and cycling, and T2, between cycling and running. These changeovers are sometimes described as the sport's “fourth discipline.”

The modern triathlon developed in the United States during the 1970s, particularly through races associated with Southern California. It became an Olympic sport at the 2000 Sydney Games. Olympic triathlon uses a shorter course than the famous Ironman distance: the standard Olympic format is a 1.5-kilometer swim, 40-kilometer cycle, and 10-kilometer run.

Triathlon is easy to confuse with related multi-sport events. A duathlon combines running, cycling, and running, while an aquathlon combines swimming and running. The Olympic modern pentathlon includes swimming and running but also fencing, horse jumping, and shooting, so it is not the answer to this question.