swimming is a good for health

I don't really like to swim. But I swim a lot because it is very good for health. It is the no.1 calories burner and unlike many of the aerobic exerices, it does not hurt the knee (running places great stress on the knee, for example) I usually go to swimming pool to swim and enjoy some sun-bathing at the same time. Well, the pool water is not very good for the skin, but you have to choose. I don't like to go to beach because of the sea water, they're salty and make my eyes and throat dry. Also, I hate that my legs are dirtied with sands.