In examining the relative efficiency of human athletes running and swimming, the following statistics are graphed: 1) ratio of swimming time to running time to traverse a fixed distance; 2) the ratio of running distance to swimming distance in a fixed amount of time; 3) efficiency of swimming to running (energy required for each) over time elapsed; and 4) swimming to running energy (joules/second) over time. It is concluded that: 1) swimmers can (and do) exert about 25% more energy per second than do comparable runners; and 2) runners traverse about 3.5 times the distance that comparable swimmers do in the same amount of time. An important point of this article is methodical. One can describe the relative efficiency of locomotion with a statistic that conditions on time or distance. But which is more suitable depends on the prospective use. If we wish to know how many calories an athlete needs to traverse a particular distance, conditioning on distance is the obviously correct statistic. When looking at relative efficiency (ratios) conditioning on time has clear interpretive advantages.