A swimmer of average ability can swim at a speed of about 2 miles per hour. This is roughly similar to swimming the 50-meter length of an Olympic-sized pool in 56 seconds.
Swimming speed is determined by a number of factors, including the swimmer’s physical condition, level of training, and stroke technique. The front crawl is the fastest and most efficient stroke for most swimmers. A swimmer in good shape can swim faster than 4 miles per hour using the front crawl with sufficient training. The current world record for the 50-meter crawl is 20.91 seconds, which equates to 5.39 miles per hour in the water.