Why is the swim so short relative to the bike and run in triathlons?

Question

The origin of the distances for the Ironman triathlon were discussed in a previous question, but it seems odd that almost every triathlon I see, the swim section is incredibly short in comparison to the running and biking section. Why aren't triathlons set up to be 1:1:1 in either distance (e.g. 1 mile each), or in time (e.g. how far a 95th percentile athlete in each sport can go in an hour)?

If anything, I would think that the swimming section should be proportionally more, since it's the only part that substantially works the upper body.

Answer 1

A short distance in water does not necessarily mean an easy swim. You exert yourself much more (lower and upper body) in the same distance and time while swimming. If you swim at all, picture yourself at a lake with a dock on the other side of a typical cove. If the lake bed was dry, and you jogged over to the dock, you would hardly have time to get your heart-rate up. But swim to that dock in the water and you will be winded and it will take more time. If the distances were 10 miles-10miles-10miles, the swim portion would take forever, and only the most elite of athletes would even finish. If the distances were, say 1mile-1mile-1mile. This would be an endurance swim, but almost a sprint run, and definitely a sprint bike. Most standard triathlons are endurance events and if anything they are designed so that you spend more time running and biking.