Water is Heavy!
Believe it or not, a gallon of water weighs eight pounds! If you live near a beach, try the following experiment. Wade out from the shoreline until the water is a foot deep. Next, run a 100, 200, or 400 (parallel to the shoreline) as fast as possible and see how tired you get. Now imagine if you ran the same distance with your entire body in the water because that’s what you do when you swim. Whether you get to try the experiment or not, the point is pretty straightforward, water is heavy, and the more pulling and kicking strength you possess, the faster you’ll swim through it. On a side note, better streamlining off the walls and more streamlined strokes also make swimming faster easier to do.