The answer to this question depends on how much you weigh and how hard you stroke ;-). The more you weigh, the more mass you have to pull through the water and the more calories you burn/min. Obviously the harder you work, the more calories you burn. There are lots of places on the web where you can get the answer to this question.
For example 1 150 pound person swimming breaststroke for 60 minutes, burns 714 calories.
You can burn as many as 100 calories per hour just swimming casually in salt water. You can burn up to 500 calories per hour if you're swimming vigorously.
How many calories are burned when swimming depends on the person's weight and the size of the pool. For a person who weighs 150 pounds in a pool that is 25 yards in length they will burn 414 calories for an hour of doing a front crawl.
a lot !=]
300
300 calories.
150 Calories.
5000 if you do it correctly.
500 per hour average
350/hour
600 calories.
No
Around 50 a hour