The triathlon is an event that involves swimming, cycling and running, in that order.  One of the most well known triathlon events is the Iron-man, with the world championships held in Hawaii each year.  There are other triathlon lengths, including the Half Iron-man, the Olympic distance (used at the Summer Olympic Games) and various Sprint distances that are often determined by the sponsoring event.

This table shows the typical distances.  You will note that the running length follows after the typical running race lengths of 10K, half marathon and marathon.