swimming for exercise

[rawcenter]

I usually walk for exercise and thats about it. maybe some resistance training situp pushups or pullups. I was thinking about swiming laps or something but Im not too sure how long to do this for to get a decent workout? should I just keep doing it until I cant anymore... Also is there a website that tells you what diff types of exercise burns how many calories? So when I have a limited amount of time to work out I can choose the appropriate exercise that would be of the most benefit.
thanks for any input =)

[ArcticMist]

I dont know how much you should do. But when I could swim during the summer I really lost some weight.. I wish I could do it a few times a week.

[mindelicious]

I avoid swimming pools, jacuzzis, etc at all costs. There are so many chemicals put into the water to keep it crystal clear and "clean". I do swim in the ocean or other bodies of water that are not stagnant or man made.
If you do decide to continue swimming in pools rinse your body beforehand in shower, etc, then maybe your body will not absorb so much of the chemical water.