Swimming is great for dropping weight. I was a top swimmer when I was a kid in High School. Last year when I went to swim with my wife who does water arobics I couldn't swim accross the short lenght of the pool! :~) I grabbed a paddle board and just kicked back and forth the lenght of the pool for a half hour each day. By the end of the second month or so I could swim the lenght of the pool face down and back stroke the way back without stopping! I also trimmed about 20 pounds in the process and I started out at 190 pounds at 6 feet tall so I wan'nt overweight to start with. Just carried a spare tire around my middle from driving so much the past 5 years for my job.
Hope this helps some?