I swam a kilometer yesterday. It took me about a half an hour. I was just about on my last lap, and a kid stopped me after about 800m and asked me how it was possible that I could swim so fast for so long. He said that he had been trying to do one for my three and was having a hard time keeping up. I told him that I wasn't in good shape at all, I haven't even been swimming in a couple of years, but that I did know how to swim, and that that fact alone makes a huge difference.
I'm sure that Jeff could do a kilometer in about half the time it took me, or even less. Maybe it shouldn't strike me as being odd that most people don't know how to swim even though they can swim. The same way millions of people take photographs without really know how to take photographs.
Jeff posted a comment, and I just want to make sure that his swimming tips don't go missing somehow.
Some basics that I would advise would be to make sure your body position is level in the water, keep your head down, breath about once for every three strokes, and count your strokes per length.
If you can reduce the number of strokes it takes to get across the pool even by a couple of strokes you will probably find yourself going faster and using less energy.
In any case, I wish I had a little more to write about, but it seems like I always forget my ideas by the time I get home. Especially when they are good ideas.